Green’s Dictionary of Slang

1. caterwauling, making a noise; also as adj.; also as molrow n. + v.

1834		Hereford Times 12 July 4/4: Yes [...] me and master have both got up together to stop her molrowing.
1836		‘The Blue Devils Now’ in New Cockalorum Songster in Spedding & Watt (eds) II 14: The dog he kept youling, the cat molrow cries.
1836		‘The Doleful Tragedy’ in New Cockalorum Songster in Spedding & Watt (eds) Bawdy Songbooks (2011) II 23: Puss saw her mistress turning pale, / Molrowed three times and swell’d her tail.
1840		R.B. Peake Devil In London I iv: The man wot crows, the person wot molrows, the individual wot brays.
1853		Bell’s Life in Sydney 27 Aug. 2/7: Tommy was certainly in the practise of ascending the roof of a night and crying ‘moll-row‘ like other Tom-cats.
1854		N.Y. Pick (NY) 29 Apr. n.p.: Duo in A Sharp. — Mol row! Mol row! with variations extempore, by sundry members of the feline race.
c.1860		‘What Shall We Do For Meat!’ in C. Hindley Curiosities of Street Lit. (1871) 127: She would be moll-rowing all the night, / And mewing in the morning.
1865		Leaves from Diary of Celebrated Burglar 47/1: With one blow from his ‘neddy’ [Joe] laid the poor cat lifeless, exclaiming: ‘There, you moll-rowing devil; take that for showing your “mug” where ’twasn’t wanted’.
1879		Star (Guernsey) 19 July 4/6: Their cats are before us, / Molrowing in chorus.
1882		Bristol Magpie 14 Sept. 6/1: Some well-known pathetic air / [...] / Like cats’ ‘molrow’ with distant watch dog howling.
1882		Taunton Courier 1 Mar. 7/2: The molrowing Tommies and Tibbies, that are wont to make night hideous by their amatory melodies on the tiles.
1894		G.A. Sala Things I Have Seen II 121: Cats [...] whose diabolical moll-rowings still ring in my ears.

2. going out on a (whoring) spree; thus molrow v.

1860		Hotten Dict. of Modern Sl. etc.
1873		Sl. Dict.
1896		Farmer Vocabula Amatoria (1966) 83: Courtisaner. To whoremonger; ‘to molrow’.