Green’s Dictionary of Slang

the woman with whom a man cohabits.

1727		J. Gay Beggar’s Opera III v: To Mrs. Diana Trapes, the Tally-Woman and she will make a good Hand on’t in Shoes and Slippers, to trick out young Ladies, upon their going into Keeping.
1773		Harris’s List of Covent-Garden Ladies 11: Mrs. Williams, an old crony of the celebrated tally woman Judith Veale.
1788		G.A. Stevens Adventures of a Speculist I 250: Their cloaths they hire of a tally-woman, with whom their mistress goes snacks.
1864, 1867, 1870		Hotten Sl. Dict.
1875		Manchester Eve. News 31 Aug. 2/4: She answered, ‘It is very hard to be locked up for beating my husband’s tally wife’.
1882		Sydney Sl. Dict. (2 edn) 11: ‘[T]ally-wife,’ a woman who cohabits with a man without marriage.
1888		S.O. Addy Sheffield Gloss. 251: Tally-qwoman, a married man’s mistress or concubine.
1969		Tennessean (Nashville, TN) 14 Dec. 5/3: A tally-wife is a mistress.