diff --git a/src/rustc/metadata/encoder.rs b/src/rustc/metadata/encoder.rs
index e1ed9fe396a..6f4716208a2 100644
--- a/src/rustc/metadata/encoder.rs
+++ b/src/rustc/metadata/encoder.rs
@@ -421,7 +421,7 @@ fn encode_info_for_mod(ecx: @encode_ctxt, ebml_w: ebml::writer, md: _mod,
           }
           _ {
             // Must be a re-export, then!
-            // ...or an iface ref
+            // ...or a trait ref
             ebml_w.wr_str(def_to_str(did));
           }
         };
diff --git a/src/rustc/middle/kind.rs b/src/rustc/middle/kind.rs
index 81d87e9d291..34529710825 100644
--- a/src/rustc/middle/kind.rs
+++ b/src/rustc/middle/kind.rs
@@ -466,7 +466,7 @@ fn check_owned(tcx: ty::ctxt, ty: ty::t, sp: span) -> bool {
 }
 
 /// This is rather subtle.  When we are casting a value to a
-/// instantiated iface like `a as iface/&r`, regionck already ensures
+/// instantiated trait like `a as trait/&r`, regionck already ensures
 /// that any borrowed pointers that appear in the type of `a` are
 /// bounded by `&r`.  However, it is possible that there are *type
 /// parameters* in the type of `a`, and those *type parameters* may
@@ -475,14 +475,14 @@ fn check_owned(tcx: ty::ctxt, ty: ty::t, sp: span) -> bool {
 ///
 /// Therefore, we ensure that one of three conditions holds:
 ///
-/// (1) The iface instance cannot escape the current fn.  This is
+/// (1) The trait instance cannot escape the current fn.  This is
 /// guaranteed if the region bound `&r` is some scope within the fn
 /// itself.  This case is safe because whatever borrowed pointers are
 /// found within the type parameter, they must enclose the fn body
 /// itself.
 ///
-/// (2) The type parameter appears in the type of the iface.  For
-/// example, if the type parameter is `T` and the iface type is
+/// (2) The type parameter appears in the type of the trait.  For
+/// example, if the type parameter is `T` and the trait type is
 /// `deque<T>`, then whatever borrowed ptrs may appear in `T` also
 /// appear in `deque<T>`.
 ///
@@ -493,7 +493,7 @@ fn check_cast_for_escaping_regions(
     source: @expr,
     target: @expr) {
 
-    // Determine what type we are casting to; if it is not an iface, then no
+    // Determine what type we are casting to; if it is not an trait, then no
     // worries.
     let target_ty = ty::expr_ty(cx.tcx, target);
     let target_substs = alt ty::get(target_ty).struct {
@@ -501,7 +501,7 @@ fn check_cast_for_escaping_regions(
       _ => { ret; /* not a cast to a trait */ }
     };
 
-    // Check, based on the region associated with the iface, whether it can
+    // Check, based on the region associated with the trait, whether it can
     // possibly escape the enclosing fn item (note that all type parameters
     // must have been declared on the enclosing fn item):
     alt target_substs.self_r {
@@ -514,8 +514,8 @@ fn check_cast_for_escaping_regions(
       }
     }
 
-    // Assuming the iface instance can escape, then ensure that each parameter
-    // either appears in the iface type or is owned:
+    // Assuming the trait instance can escape, then ensure that each parameter
+    // either appears in the trait type or is owned:
     let target_params = ty::param_tys_in_type(target_ty);
     let source_ty = ty::expr_ty(cx.tcx, source);
     do ty::walk_ty(source_ty) |ty| {
diff --git a/src/rustc/middle/resolve3.rs b/src/rustc/middle/resolve3.rs
index 8b40d8136ab..c49a6889f05 100644
--- a/src/rustc/middle/resolve3.rs
+++ b/src/rustc/middle/resolve3.rs
@@ -3365,7 +3365,7 @@ class Resolver {
                     none {
                         self.session.span_err(interface.path.span,
                                               ~"attempt to implement a \
-                                               nonexistent interface");
+                                               nonexistent trait");
                     }
                     some(def) {
                         // Write a mapping from the interface ID to the
diff --git a/src/rustc/middle/ty.rs b/src/rustc/middle/ty.rs
index e58de56703a..a2ba9277fd0 100644
--- a/src/rustc/middle/ty.rs
+++ b/src/rustc/middle/ty.rs
@@ -1611,7 +1611,7 @@ fn type_kind(cx: ctxt, ty: t) -> kind {
         remove_send(mutable_type_kind(cx, tm) | kind_safe_for_default_mode())
       }
 
-      // Iface instances are (for now) like shared boxes, basically
+      // Trait instances are (for now) like shared boxes, basically
       ty_trait(_, _) { kind_safe_for_default_mode() | kind_owned() }
 
       // Region pointers are copyable but NOT owned nor sendable
@@ -1711,7 +1711,7 @@ fn type_kind(cx: ctxt, ty: t) -> kind {
         param_bounds_to_kind(cx.ty_param_bounds.get(p.def_id.node))
       }
 
-      // self is a special type parameter that can only appear in ifaces; it
+      // self is a special type parameter that can only appear in traits; it
       // is never bounded in any way, hence it has the bottom kind.
       ty_self { kind_noncopyable() }
 
diff --git a/src/rustc/middle/typeck/check/method.rs b/src/rustc/middle/typeck/check/method.rs
index 6f1e97bc342..585d0ccf5cf 100644
--- a/src/rustc/middle/typeck/check/method.rs
+++ b/src/rustc/middle/typeck/check/method.rs
@@ -258,7 +258,7 @@ class lookup {
                 self.tcx().sess.span_err(
                     self.expr.span,
                     ~"can not call a method that contains a \
-                     self type through a boxed iface");
+                     self type through a boxed trait");
             }
 
             if (*m.tps).len() > 0u {
diff --git a/src/rustc/middle/typeck/check/regionck.rs b/src/rustc/middle/typeck/check/regionck.rs
index b307460628a..850181576ab 100644
--- a/src/rustc/middle/typeck/check/regionck.rs
+++ b/src/rustc/middle/typeck/check/regionck.rs
@@ -137,9 +137,9 @@ fn visit_expr(e: @ast::expr, &&rcx: @rcx, v: rvt) {
       }
 
       ast::expr_cast(source, _) {
-        // Determine if we are casting `source` to an iface instance.
+        // Determine if we are casting `source` to an trait instance.
         // If so, we have to be sure that the type of the source obeys
-        // the iface's region bound.
+        // the trait's region bound.
         //
         // Note: there is a subtle point here concerning type
         // parameters.  It is possible that the type of `source`
@@ -155,12 +155,12 @@ fn visit_expr(e: @ast::expr, &&rcx: @rcx, v: rvt) {
           result::ok(target_ty) => {
             alt ty::get(target_ty).struct {
               ty::ty_trait(_, substs) {
-                let iface_region = alt substs.self_r {
+                let trait_region = alt substs.self_r {
                   some(r) => {r}
                   none => {ty::re_static}
                 };
                 let source_ty = rcx.fcx.expr_ty(source);
-                constrain_regions_in_type(rcx, iface_region,
+                constrain_regions_in_type(rcx, trait_region,
                                           e.span, source_ty);
               }
               _ { }
diff --git a/src/rustc/middle/typeck/check/vtable.rs b/src/rustc/middle/typeck/check/vtable.rs
index 51a412be718..f023f3aeae7 100644
--- a/src/rustc/middle/typeck/check/vtable.rs
+++ b/src/rustc/middle/typeck/check/vtable.rs
@@ -100,11 +100,11 @@ fn lookup_vtable(fcx: @fn_ctxt, sp: span, ty: ty::t, trait_ty: ty::t,
             for vec::each(*ty::trait_methods(tcx, did)) |m| {
                 if ty::type_has_self(ty::mk_fn(tcx, m.fty)) {
                     tcx.sess.span_err(
-                        sp, ~"a boxed iface with self types may not be \
+                        sp, ~"a boxed trait with self types may not be \
                              passed as a bounded type");
                 } else if (*m.tps).len() > 0u {
                     tcx.sess.span_err(
-                        sp, ~"a boxed iface with generic methods may not \
+                        sp, ~"a boxed trait with generic methods may not \
                              be passed as a bounded type");
 
                 }
diff --git a/src/rustc/middle/typeck/collect.rs b/src/rustc/middle/typeck/collect.rs
index 60c79407e6d..d695101f877 100644
--- a/src/rustc/middle/typeck/collect.rs
+++ b/src/rustc/middle/typeck/collect.rs
@@ -195,7 +195,7 @@ fn compare_impl_method(tcx: ty::ctxt, sp: span,
 
     if vec::len(impl_m.fty.inputs) != vec::len(if_m.fty.inputs) {
         tcx.sess.span_err(sp,#fmt["method `%s` has %u parameters \
-                                   but the iface has %u",
+                                   but the trait has %u",
                                   *if_m.ident,
                                   vec::len(impl_m.fty.inputs),
                                   vec::len(if_m.fty.inputs)]);
@@ -398,7 +398,7 @@ fn convert(ccx: @crate_ctxt, it: @ast::item) {
         let cms = convert_methods(ccx, methods, rp, bounds, selfty);
         for traits.each |trt| {
             check_methods_against_trait(ccx, tps, rp, selfty, trt, cms);
-            // trt.impl_id represents (class, iface) pair
+            // trt.impl_id represents (class, trait) pair
             write_ty_to_tcx(tcx, trt.impl_id, tpt.ty);
             tcx.tcache.insert(local_def(trt.impl_id), tpt);
         }
@@ -455,7 +455,7 @@ fn ty_of_ty_method(self: @crate_ctxt,
 fn instantiate_trait_ref(ccx: @crate_ctxt, t: @ast::trait_ref, rp: bool)
     -> (ast::def_id, ty_param_substs_and_ty) {
 
-    let sp = t.path.span, err = ~"can only implement interface types",
+    let sp = t.path.span, err = ~"can only implement trait types",
         sess = ccx.tcx.sess;
 
     let rscope = type_rscope(rp);
diff --git a/src/test/compile-fail/class-implements-int.rs b/src/test/compile-fail/class-implements-int.rs
index 513b539a45e..ccc821ce78a 100644
--- a/src/test/compile-fail/class-implements-int.rs
+++ b/src/test/compile-fail/class-implements-int.rs
@@ -1,4 +1,4 @@
-class cat : int { //~ ERROR interface
+class cat : int { //~ ERROR trait
   let meows: uint;
   new(in_x : uint) { self.meows = in_x; }
 }
diff --git a/src/test/compile-fail/iface-impl-different-num-params.rs b/src/test/compile-fail/iface-impl-different-num-params.rs
index 094dc7ac062..9c51f56e54c 100644
--- a/src/test/compile-fail/iface-impl-different-num-params.rs
+++ b/src/test/compile-fail/iface-impl-different-num-params.rs
@@ -3,7 +3,7 @@ iface foo {
 }
 impl of foo for int {
     fn bar() -> int {
-        //~^ ERROR method `bar` has 0 parameters but the iface has 1
+        //~^ ERROR method `bar` has 0 parameters but the trait has 1
         self
     }
 }
diff --git a/src/test/compile-fail/issue-2330.rs b/src/test/compile-fail/issue-2330.rs
index b0b21051714..9bbba8f5caf 100644
--- a/src/test/compile-fail/issue-2330.rs
+++ b/src/test/compile-fail/issue-2330.rs
@@ -4,8 +4,8 @@ iface channel<T> {
     fn send(v: T);
 }
 
-// `chan` is not an iface, it's an enum
-impl of chan for int { //~ ERROR can only implement interface types
+// `chan` is not a trait, it's an enum
+impl of chan for int { //~ ERROR can only implement trait types
     fn send(v: int) { fail }
 }
 
diff --git a/src/test/compile-fail/selftype-astparam.rs b/src/test/compile-fail/selftype-astparam.rs
index df7f8cd6cad..64699267c4d 100644
--- a/src/test/compile-fail/selftype-astparam.rs
+++ b/src/test/compile-fail/selftype-astparam.rs
@@ -11,5 +11,5 @@ fn do_add<A:add>(x: A, y: A) -> A { x.plus(y) }
 fn main() {
     let x = 3 as add;
     let y = 4 as add;
-    do_add(x, y); //~ ERROR a boxed iface with self types may not be passed as a bounded type
+    do_add(x, y); //~ ERROR a boxed trait with self types may not be passed as a bounded type
 }
diff --git a/src/test/compile-fail/selftype-ifacetype.rs b/src/test/compile-fail/selftype-ifacetype.rs
index a4bd394d529..c4ba8093886 100644
--- a/src/test/compile-fail/selftype-ifacetype.rs
+++ b/src/test/compile-fail/selftype-ifacetype.rs
@@ -3,7 +3,7 @@ iface add {
 }
 
 fn do_add(x: add, y: add) -> add {
-    x.plus(y) //~ ERROR can not call a method that contains a self type through a boxed iface
+    x.plus(y) //~ ERROR can not call a method that contains a self type through a boxed trait
 }
 
 fn main() {}