A ham radio operator who has died.

(management) A financial or non-financial metric used to help an organization define and measure progress towards its goals.

The log which, if removed, would free up the whole logjam.

(nautical) A type of keel common in sailing yachts, its shape resembling the fin of a fish.

(video games) A downloadable content file that unlocks items, characters, levels, or other content that was included with a video game but not immediately accessible (if at all through normal gameplay).

(botany) A widely-dispersed, but rare, tree, Gymnocladus dioicus, native to the midwest of North America.

(computing) A key, or key combination, which, when pressed, causes something to happen.

A type of rough woollen cloth.

To keep one's own business private; to be discreet, careful, or circumspect in what one says concerning one's own thoughts, deeds, or situation.

(idiomatic) To keep a secret; to refrain from speaking indiscreetly or carelessly; broadly, to refrain from speaking altogether.