Definition of "sinister"

All the several ills that visit earth,Brought forth by night, with a sinister birth.

1611, Ben[jamin] Jonson, Catiline His Conspiracy, London: […] [William Stansby?] for Walter Burre, (please specify |act=I to V)

And in the meanwhile, Society shivered a little feverishly, filled now with the scions of those who had come over with the Jewish and American Conquests. Escutcheons were becoming valueless, how sinister soever the blots and clots upon them.

1922, Michael Arlen, “1/5/1”, in “Piracy”: A Romantic Chronicle of These Days‎

my Mothers bloudRuns on the dexter checke, and this ſiniſterBounds in my fathers:

c. 1602, William Shakespeare, “The Tragedie of Troylus and Cressida”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene v], column 2

His ſicatrice, with an Embleme of warre, heere on his ſiniſter cheeke;

c. 1604–1605 (date written), William Shakespeare, “All’s Well, that Ends Well”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene i], page 235

Before the train had stopped he had decorated his sinister shirt-cuff with the inscription, ‘J. P. Huddle, The Warren, Tilfield, near Slowborough.’

1911, Saki, ‘The Unrest-Cure’, The Chronicles of Clovis

Nimble and sinister tricks and shifts.

1625, Francis [Bacon], “Of Judicature”, in The Essayes […], 3rd edition, London: […] Iohn Haviland for Hanna Barret

He scorns to undermine another's interest by any sinister or inferior arts.

1667, Robert South, The Practice of Religion Enforced by Reason

He read in their looks […] sinister intentions directed particularly toward himself.

1822, [Walter Scott], The Pirate. […], volumes (please specify |volume=I to III), Edinburgh: […] [James Ballantyne and Co.] for Archibald Constable and Co.; London: Hurst, Robinson, and Co.