Green’s Dictionary of Slang

a woman living away from her husband; specifically (Anglo-Ind.) one residing for the summer in a hill station, or one living in Britain while her husband is stationed in India; the parallel use in Aus. may be asumed to be have been imported .

1841		Flash (NY) 26 Sept. n.p.: [of a woman whose husband is in prison] [He] was at last sent to Sing Sing [...] leaving his grass widow and his own wordly goods.
1843		Satirist & Sporting Chron. (Sydney) 18 Feb. 3/1: SEAHORSE, STEAMER, a crack boat, crack owners, and cra[c]k Captain. What a pity such a young man as Tallan, should PAY so much attention to the Grass Widow - in other respects this Skipper's foibles are excusable.
1851		Western Police Gaz. (Cincinnati, OH) 29 Mar. n.p.: You must have ben egregiously sorry for that old ‘Grass Widow’.
1851		R.F. Burton Goa, and the Blue Mountains 295: Among the ladies, we have elderlies who enjoy tea and delight in scandal: grass widows – excuse the term, being very much wanted, it is commeilfaut in this region – and spinsters of every kind.
1860		E.A. Langley Narrative of a Residence at the Court of Meer Ali Moorad I 166: Such a desertion of young wives for a long period of years can, however, hardly contribute to morality, and the consequence is, that many of ‘the grass widows’ form other connections in the absence of their liege lords, who, however, seem to take the thing very philosophically.
1867		Nat. Police Gaz. (NY) 28 Dec. 2/3: Most of the inmates of the parlor houses are [...] what are termed ‘grass widows,’ — i.e. those who have been deserted by their husbands, and who seek a life of shame through necessity .
[1869		H. Smart Breezie Langton I 36: ‘[H]e’s lost his heart to a widow in “the grazing way”’].
1868		F. Marryat ‘Gup’ 101: There are always plenty of females on the hills, consequently the hills are dangerous to an idle man. There are the wives who can’t live with their husbands in the plains; the ‘grass-widows’ (or widows put out to grass), as they are vulgarly termed.
1877		Chambers’s Jrnl 12 Mar. 173: Mrs. Brittomart was one of those who never tolerated a bow-wow – a species of animal well known in India – and never went to the hills as a ‘grass-widow’ .
1885		Bulletin (Sydney) 15 Aug. 20/2: The Delilah, a fie-fie, florid, flashy grass-widow, who flaunted her ‘aureoline tresses,’ her powdered-painted cheeks, her kohl’d eyes, and her pinched-in waist on the quarter-deck, on sunny Sabbath mornings.
1886		Yule & Burnell Hobson-Jobson 301/2: Grass-Widow, s. This slang phrase is applied in India, with a shade of malignity, to ladies living apart from their husbands, especially as recreating at the Hill stations, whilst the husbands are at their duties in the plains.
1889		Nat. Police Gaz. (NY) 16 Nov. 3/1: [headline] wily wicked widows / Even the Brand Called Grass Widows Are Not Green / they fool innocent man / And Knock Him Silly with their Quaint, Fascinating Ways / isn’t it dreadfully awful? / Just Read How Awfully Dangerous it Is for Unprotected Men / let us take the the woods.
1892		[Edith Cuthell] In Tent and Bungalow 58: Prayte had, of course, gone through the fire years before. He had had his grandes passions for giddy grass-widows on the hills, his cooler intellectual friendships with kindred souls during the cold weather on the plains.
1895		Crowe Aus. Sl. Dict. 33: Grass Widow, the wife being away from the husband.
1901		W.A. Sun. Times (Perth) 28 July 1/1: A boss-joss journalist of Perth has succumbed to the winsome wink of a local grass widow.
1904		Sun. Times (Perth) 24 Jan. 1/1: His grass widow girlie has demanded a new pair of boots!!
1908		J. Ayscough Mr. Beke of the Blacks I 183: It was not at all a clever thing to annoy the two young women [...] ‘and all for the sake of a grass widow, whom every one barred; with no looks, and not up to sample in any way’.
1909		J. Ware Passing Eng. of the Victorian Era 12/1: Away (London Thieves’ Etiquette), A man is never spoken of as ‘in prison’, though he is there for many a ‘stretch’. [...] ‘Mine’s away, bless ’is ’art,’ the grass-widow of lower life will say, as indication that her husband is in jail.
1910		Sun. Times (Perth) 14 Aug. 1st sect. 1/1: That the hoary-headed barman is still in the toils of the grass -widow. That the gin-jerker is duplicating his old-time Subiaco doings.
1911		Civil & Milit. Gaz. (Lahore) 23 Apr. 7/1: Mrs. Graham as the merry grass widow in her song ‘I’m off to Simla!’ was charming.
1928		C. McKay Home to Harlem 82: ‘He was living sweet.’ There was something so romantic about the sweet life. To be the adored of a Negro lady of means, or of a pseudo grass-widow whose husband worked on the railroad, or of a hard-working laundress or cook. It was much more respectable and enviable to be sweet—to belong to the exotic aristocracy of sweetmen.
1941		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 25 Oct. 9/6: What’s that certain ‘grass widow’ going o do since Marcellette’s moved to Mount Vernon.