(literally) A turn in a vehicle carried out by driving in a semicircle in order to travel in the opposite direction. / (figuratively) A reversal of policy; an about-face, a backflip.

To turn a vehicle in a semicircle so as to face the opposite direction. / (intransitive) To shift from one opinion or decision to its opposite.

(military, nautical, historical) Any German submarine of the First or Second World War, or any Austro-Hungarian submarine of the First World War.

(chiefly Britain, colloquial, dated) Not U; not characteristic of the upper classes, particularly regarding language.

thermal transmittance or thermal conductance

(linguistics) The form of Received Pronunciation used by the upper classes.

(linguistics) The sound /juː/, as in the words "cube" and "mute".

(linguistics) The vowel sound, /ʌ/, in the words "cut" and "run".

A person or vehicle that performs a U-turn. / Someone who shifts from a previously held opinion or decision to its opposite.

plural of U-turner