Green’s Dictionary of Slang

1. to coerce, to persuade.

1826		[W.B. Hockley] Pandurang Hàrì 158: Oftentimes the arbitrators are all in league, and divide whatever comes to the net in equal portions: – in this case they apply themselves to sumjao the defendant.
1839		R. Neave ‘Syud Kurrum Ally’ in Parbury’s Oriental Herald III 350: It is [...] celebrated for [...] the fertility of the soil in its vicinity, in which potatoes, sugar-cane, and indigo, are produced with prolific prodigality, wherever the collector has not sumjaowed the owner into cultivating the poppy.
1848		J.H. Stocqueler Oriental Interpreter 216/2: SUMJOW, a Hindostanee word, literally not to be translated, but most significant in its usage. It comes from Sumujha, to cause to understand, or to persuade; but the means of persuasion, whether argument or force, are ingeniously left to the conception of those whose interests it suits, in which case the interpretation rests with the most powerful.
1873		Allen’s Indian Mail 1 Sept. 807/1: The Commissioner of Scinde or the Superintendent of the Frontier – we are not sure which – advised, or, to use the expressive hybrid vernacular term (Sumjaoed), the Khan to dismiss these mischief-making servants, and his Highness did so.
1886		Yule & Burnell Hobson-Jobson xix: One peculiarity in this use we may notice, which doubtless exemplifies some obscure linguistic law. Hindustani verbs which are thus habitually adopted quasi-English by converting imperative into an infinitive. Thus to bunow, to lugow, to foozilow, to puckarow, to dumbcow, to sumjow, and so on [...] are formed as we have indicated.
1894		R.G. Sanyal Reminiscences and Anecdotes of Great Men of India 123: He was however sumjaod and yielded afterwards.
1903		W. Crooke in Yule & Burnell Hobson-Jobson 868/1: SUMJAO, v. This is properly the imp. of the H. verb samjh?n?, ‘to cause to know, warn, correct,’ usually with the implication of physical coercion.

2. to know, to understand.

1841		F.J. Bellew ‘Memoirs of a Griffin’ in Asiatic Jrnl & Mthly Register May 53: Smirks, our adjutant [...] bucking up to and devilish sweet on the spinster; but it won’t hoga (do); nothing under the revenue or judicial department will go down there – Samjah Sahib? – You understand me.
1888		Kipling ‘The God from the Machine’ in Soldiers Three (1890) 18: ‘Take him away, an’ av you iver say wan wurrd about fwhat you’ve dekkoed, I’ll marrow you till your own wife won’t sumjao who you are!’.