Contraction, n.
Etymology: [L. contractio: cf. F. contraction.]
1. The act or process of contracting, shortening, or shrinking; the state of being contracted; as, contraction of the heart, of the pupil of the eye, or of a tendion; the contraction produced by cold.
2. (Math.)
The process of shortening an operation.
3. The act of incurring or becoming subject to, as liabilities, obligation, debts, etc.; the process of becoming subject to; as, the contraction of a disease.
4 more senses
4. Something contracted or abbreviated, as a word or phrase; -- as, plenipo for plenipotentiary; crim. con. for criminal conversation, etc.
5. (Gram.)
The shortening of a word, or of two words, by the omission of a letter or letters, or by reducing two or more vowels or syllables to one; as, ne'er for never; can't for can not; don't for do not; it's for it is.
6. A marriage contract. [Obs.] Shak.
Shades of meaning
Fernald has no entry of its own for contraction; he lists it under abbreviation.
Where he writes about it:
An abbreviation is a shortening by any method; a contraction is a reduction of size by the drawing together of the parts. — from abbreviation
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 either 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; rec't for receipt, mdse. for merchandise, and Dr. for debtor are contractions; they are also abbreviations; Am. for American is an abbreviation, but not a contraction. — from abbreviation
Abbreviation and contraction are used of words and phrases, abridgment of books, paragraphs, sentences, etc. — from abbreviation