by-stroke

== English == === Alternative forms === bystroke === Etymology === From by- +‎ stroke. === Noun === by-stroke (plural by-strokes) An incidental or slyly given stroke; a gratuitous addition or indirect action. 1907, Caroline Lane Reynolds Slemmer Jebb (lady.), Arthur Woollgar Verrall, Life and letters of Sir Richard Claverhouse Jebb, O. M., LITT. D.: We must be content to signalize a by-stroke of sympathetic delicacy. A secondary attack.