Describing a situation in which there are only two choices. / Describing a situation in which there is a choice between two different plans of action, but both together are not possible

plural of fill or kill

(stock market) A type of stock market or financial derivative order, signifying that the order is to be presented for execution, and if not executed ("filled") immediately (traditionally within a few seconds) is to be cancelled.

double or quits

(mathematics) In morphology, an operation that detects a given configuration (or pattern) in a binary image, using the erosion operator and a pair of disjoint structuring elements.

plural of hit-or-miss transform

(chiefly US, informal) Used to indicate one's intention to do everything possible to achieve a goal, with failure being the only alternative.

(proscribed) Seldom, if ever; rarely or not at all.

(informal) Used to indicate that something is the case and cannot be altered even if the listener does not want it to be the case.

Third-person singular simple present indicative form of make head or tail of