(logic) A kind of non-classical propositional calculus whose semantics makes use of more than two truth values.

Dead branches or wood on a tree, or coarse woody debris. / People or things judged to be superfluous to an organization or project. / Money not realized by exiting a winning pump trade too early.

A protein found in Hyriopsis cumingii and involved in nacre formation.

Alternative spelling of back door, which can be used attributively.