We use the terms 'contracted form' and 'abbreviated form'. In theory it is both a contraction and an abbreviation, but we would generally call it a contraction. Here is part of the wikipedia entry for abbreviation: "An abbreviation is a shortening by any method; a contraction is a reduction of size by the drawing together of the parts. A contraction of a word is made by omitting certain letters or syllables and bringing together the first and last letters or elements; an abbreviation may be made by omitting certain portions from the interior or by cutting off a part. A contraction is an abbreviation, but an abbreviation is not necessarily a contraction"