(in the negative) To fail to make head or tail of; not to understand at all.

An archipelago off the coast of Cornwall, in southwestern England.

(idiomatic, chiefly in the negative, with can't/cannot) To understand even minimally. / To determine to be good or bad.

Alternative form of in two shakes

(idiomatic, humorous) An expression sometimes used when a person mentioned in the current conversation happens to arrive on the scene.

(idiomatic) An outburst of clapping among a group or audience.

(idiomatic) to commend someone's attributes to others

(Britain, slang) To have a sexual encounter with.

(physics) A supposed theory uniting all fundamental physical phenomena into a single framework.

calcium carbonate