add getAliases()

README.md

@@ -107,6 +107,12 @@ Qty.getUnits('currency'); // => [ 'dollar', 'cents' ]
 Qty.getUnits(); // => [ 'acre','Ah','ampere','AMU','angstrom']
 ```
 
+### Alternative names of a unit
+
+```javascript
+Qty.getAliases('m'); // => [ 'm', 'meter', 'meters', 'metre', 'metres' ]
+```
+
 ### Quantity compatibility, kind and various queries
 
 ```javascript

spec/quantitiesSpec.js

@@ -1251,6 +1251,14 @@ describe("js-quantities", function() {
     });
   });
 
+  describe("Qty.getAliases", function() {
+    it("should return array of alternative names for unit", function() {
+      expect(Qty.getAliases("m")).toContain("meter");
+      expect(Qty.getAliases("meter")).toContain("metre");
+      expect(Qty.getAliases("N")).toContain("newton");
+    });
+  });
+
   describe("information", function() {
     describe("bits and bytes", function() {
       it("should have 'information' as kind", function() {

src/quantities.js

@@ -523,6 +523,20 @@ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLI
     });
   };
 
+  /**
+   * Returns a list of alternative names for a unit
+   *
+   * @param {string} unit
+   * @returns {string[]} aliases for unit
+   * @throws {QtyError} if unit is unknown
+   */
+  Qty.getAliases = function(unitName) {
+    if (!UNIT_MAP[unitName]) {
+        throw new QtyError('Unit not recognized');
+    }
+    return UNITS[UNIT_MAP[unitName]][0];
+  };
+
   /**
    * Default formatter
    *
@@ -1826,7 +1840,6 @@ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLI
       OUTPUT_MAP[unitDef] = definition[0][0];
     }
   }
-
   var PREFIX_REGEX = Object.keys(PREFIX_MAP).sort(function(a, b) {
     return b.length - a.length;
   }).join("|");