Webster's 1913 Dictionary
AIN'T
AIN'T Ain't.
Defn: A contraction for are not and am not; also used for is not. [Colloq. or llliterate speech ]. See An't.
New American Oxford Dictionary
ain't
ain't |ānt eɪnt | informal ▶contraction am not; are not; is not: if it ain't broke, don't fix it. [originally representing London dialect. ] • has not; have not: they ain't got nothing to say. [from dialect hain't . ] usage: The use of ain't was widespread in the 18th century and is still perfectly normal in many dialects and informal contexts in both North America and Britain. Today, however, it does not form part of standard English and should not be used in formal contexts.
Oxford Dictionary
ain't
ain't |eɪnt | informal ▶contraction am not; are not; is not: if it ain't broke, don't fix it. [first representing London dialect. ] • has not; have not: they ain't got nothing to say. [from dialect hain't . ] usage: The use of ain't was widespread in the 18th century, typically as a contraction for am not. It is still perfectly normal in many dialects and informal speech in both Britain and North America. Today, however, it does not form part of standard English and should never be used in formal or written contexts. See also usage at aren't .
American Oxford Thesaurus
ain't
ain't verb USAGE ain't Is this word used orally in most parts of the country by cultivated speakers? In 1961, Webster's Third New International Dictionary of the English Language (W3 ) said it was, provoking a firestorm of protests from journalists and academics. W3 's assessment was quite a change from that of W2 (the second edition, published in 1934 ), which had given it a tag: “Dial. or Illit. ” The editor of W3, Philip Gove, explained the change by conceding that he had no large files of empirical evidence: “Knowledge of some kind of language behavior comes through contact with its observers and is not always documented because there seems to be no reason to collect additional evidence. ” If that's the method, then one can confidently say that W3 's treatment was flawed in its incompleteness. In 1962, the year after W3 was published, an apt cartoon appeared in The New Yorker. A man is standing in the reception area of G. & C. Merriam Co. , Dictionary Division, as the receptionist says to him, “Sorry. Dr. Gove ain't in. ” Yes, ain't is used by cultivated speakers, but almost always for either of two reasons: (1 ) to be tongue-in-cheek, or (2 ) to flaunt their reverse snobbery. For most people, it remains a shibboleth of poor usage. Usage notes show additional guidance on finer points of English usage.
Sanseido Wisdom Dictionary
ain't
ain't /eɪnt / (!⦅話 おどけて ⦆) 1 ⦅非標準 /方言 ⦆am [are, is ] notの短縮形 (!(1 )⦅非標準 ⦆だが, しばしばくだけて用いられ, 特にain 't I …?はam I not [aren't I ] …?より好まれる. (2 )強調したりおどけて言う場合や, 決まり文句などで用いられる ) .2 ⦅非標準 ⦆have [has ] notの短縮形 .3 ⦅非標準 黒人 ⦆do [does, did ] notの短縮形 .