diff --git a/Makefile.am b/Makefile.am
index a430e5e4..c06d01a0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -88,8 +88,6 @@ UTIL_FILES   =		\
     json/tree.hpp	\
     lerp.cpp		\
     lerp.hpp		\
-    line.cpp		\
-    line.hpp		\
     log.cpp		\
     log.hpp		\
     log.ipp		\
@@ -150,6 +148,8 @@ UTIL_FILES   =		\
     range.ipp		\
     rational.cpp	\
     rational.hpp	\
+    ray.cpp		\
+    ray.hpp		\
     region.cpp		\
     region.hpp		\
     si.cpp		\
@@ -254,7 +254,7 @@ TEST_BIN = 			\
     test/hton			\
     test/ip 			\
     test/json_types		\
-    test/line			\
+    test/ray 			\
     test/maths			\
     test/maths_matrix 		\
     test/matrix			\
diff --git a/line.cpp b/ray.cpp
similarity index 82%
rename from line.cpp
rename to ray.cpp
index 857b8934..b3f9661e 100644
--- a/line.cpp
+++ b/ray.cpp
@@ -17,14 +17,14 @@
  * Copyright 2015 Danny Robson <danny@nerdcruft.net>
  */
 
-#include "line.hpp"
+#include "ray.hpp"
 
 #include "debug.hpp"
 
 
 //-----------------------------------------------------------------------------
 template <size_t S, typename T>
-util::line<S,T>::line (util::point<S,T> _p,
+util::ray<S,T>::ray (util::point<S,T> _p,
                        util::vector<S,T> _d):
     p (_p),
     d (_d)
@@ -34,13 +34,13 @@ util::line<S,T>::line (util::point<S,T> _p,
 
 
 ///----------------------------------------------------------------------------
-/// returns the distance along the line in a line-plane intersection
+/// returns the distance along the ray in a ray-plane intersection
 ///
 /// returns inf if parallel
-/// returns 0   if colinear
+/// returns 0   if corayar
 template <size_t S, typename T>
 T
-util::line<S,T>::intersect (plane<S,T> q) const
+util::ray<S,T>::intersect (plane<S,T> q) const
 {
     return dot (q.p - p, q.n) / dot (d, q.n);
 }
@@ -53,7 +53,7 @@ util::line<S,T>::intersect (plane<S,T> q) const
 /// returns -ve if behind
 template <size_t S, typename T>
 T
-util::line<S,T>::intersect (AABB<S,T> r) const
+util::ray<S,T>::intersect (AABB<S,T> r) const
 {
     auto t1 = (r.p0 - p) / d;
     auto t2 = (r.p1 - p) / d;
@@ -75,10 +75,10 @@ util::line<S,T>::intersect (AABB<S,T> r) const
 
 
 ///----------------------------------------------------------------------------
-/// returns the closest parameter along the line to a given point
+/// returns the closest parameter along the ray to a given point
 template <size_t S, typename T>
 T
-util::line<S,T>::closest (point<S,T> q) const
+util::ray<S,T>::closest (point<S,T> q) const
 {
     // project the origin-point difference onto the direction
     return dot (p - q, d);
@@ -88,12 +88,12 @@ util::line<S,T>::closest (point<S,T> q) const
 //-----------------------------------------------------------------------------
 template <size_t S, typename T>
 util::point<S,T>
-util::line<S,T>::at (T t) const
+util::ray<S,T>::at (T t) const
 {
     return p + d * t;
 }
 
 
 //-----------------------------------------------------------------------------
-template struct util::line<2,float>;
-template struct util::line<3,float>;
+template struct util::ray<2,float>;
+template struct util::ray<3,float>;
diff --git a/line.hpp b/ray.hpp
similarity index 86%
rename from line.hpp
rename to ray.hpp
index 99f45bff..e8ac7632 100644
--- a/line.hpp
+++ b/ray.hpp
@@ -17,8 +17,8 @@
  * Copyright 2015 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_LINE_HPP
-#define __UTIL_LINE_HPP
+#ifndef __UTIL_RAY_HPP
+#define __UTIL_RAY_HPP
 
 #include "point.hpp"
 #include "vector.hpp"
@@ -27,8 +27,8 @@
 
 namespace util {
     template <size_t S, typename T>
-    struct line {
-        line (util::point<S,T> origin,
+    struct ray {
+        ray (util::point<S,T> origin,
               util::vector<S,T> direction);
 
         T intersect (plane<S,T>) const;
@@ -43,8 +43,8 @@ namespace util {
     };
 
 
-    typedef line<2,float> line2f;
-    typedef line<3,float> line3f;
+    typedef ray<2,float> ray2f;
+    typedef ray<3,float> ray3f;
 }
 
 #endif
diff --git a/test/line.cpp b/test/ray.cpp
similarity index 77%
rename from test/line.cpp
rename to test/ray.cpp
index 76b497f5..f17e8516 100644
--- a/test/line.cpp
+++ b/test/ray.cpp
@@ -1,4 +1,4 @@
-#include "line.hpp"
+#include "ray.hpp"
 #include "plane.hpp"
 #include "debug.hpp"
 #include "aabb.hpp"
@@ -7,8 +7,8 @@
 void
 test_intersect_plane (void)
 {
-    // trivial case: origin line facing z, plane at unit z facing -z.
-    util::line3f  l ({0,0,0}, {0,0, 1});
+    // trivial case: origin ray facing z, plane at unit z facing -z.
+    util::ray3f  l ({0,0,0}, {0,0, 1});
     util::plane3f p ({0,0,1}, {0,0,-1});
 
     CHECK_EQ (l.intersect (p), 1);
@@ -24,7 +24,7 @@ test_intersect_aabb (void)
         { 1.f, 1.f }
     };
 
-    util::line2f l {
+    util::ray2f l {
         { 0.5f, -0.5f },
         { 0.f,   1.f }
     };