Index: Objects/floatobject.c
===================================================================
--- Objects/floatobject.c	(revision 64497)
+++ Objects/floatobject.c	(working copy)
@@ -246,6 +246,9 @@
 		if (PyOS_strnicmp(p, "inf", 4) == 0) {
 			Py_RETURN_INF(sign);
 		}
+		if (PyOS_strnicmp(p, "infinity", 9) == 0) {
+			Py_RETURN_INF(sign);
+		}
 #ifdef Py_NAN
 		if(PyOS_strnicmp(p, "nan", 4) == 0) {
 			Py_RETURN_NAN;
Index: Lib/test/test_float.py
===================================================================
--- Lib/test/test_float.py	(revision 64497)
+++ Lib/test/test_float.py	(working copy)
@@ -253,24 +253,36 @@
         floats_file.close()
 
 # Beginning with Python 2.6 float has cross platform compatible
-# ways to create and representate inf and nan
+# ways to create and represent inf and nan
 class InfNanTest(unittest.TestCase):
     def test_inf_from_str(self):
         self.assert_(isinf(float("inf")))
         self.assert_(isinf(float("+inf")))
         self.assert_(isinf(float("-inf")))
+        self.assert_(isinf(float("infinity")))
+        self.assert_(isinf(float("+infinity")))
+        self.assert_(isinf(float("-infinity")))
 
         self.assertEqual(repr(float("inf")), "inf")
         self.assertEqual(repr(float("+inf")), "inf")
         self.assertEqual(repr(float("-inf")), "-inf")
+        self.assertEqual(repr(float("infinity")), "inf")
+        self.assertEqual(repr(float("+infinity")), "inf")
+        self.assertEqual(repr(float("-infinity")), "-inf")
 
         self.assertEqual(repr(float("INF")), "inf")
         self.assertEqual(repr(float("+Inf")), "inf")
         self.assertEqual(repr(float("-iNF")), "-inf")
+        self.assertEqual(repr(float("Infinity")), "inf")
+        self.assertEqual(repr(float("+iNfInItY")), "inf")
+        self.assertEqual(repr(float("-INFINITY")), "-inf")
 
         self.assertEqual(str(float("inf")), "inf")
         self.assertEqual(str(float("+inf")), "inf")
         self.assertEqual(str(float("-inf")), "-inf")
+        self.assertEqual(str(float("infinity")), "inf")
+        self.assertEqual(str(float("+infinity")), "inf")
+        self.assertEqual(str(float("-infinity")), "-inf")
 
         self.assertRaises(ValueError, float, "info")
         self.assertRaises(ValueError, float, "+info")
@@ -278,6 +290,10 @@
         self.assertRaises(ValueError, float, "in")
         self.assertRaises(ValueError, float, "+in")
         self.assertRaises(ValueError, float, "-in")
+        self.assertRaises(ValueError, float, "infinit")
+        self.assertRaises(ValueError, float, "+Infin")
+        self.assertRaises(ValueError, float, "-INFI")
+        self.assertRaises(ValueError, float, "infinitys")
 
     def test_inf_as_str(self):
         self.assertEqual(repr(1e300 * 1e300), "inf")