To call someone without preparation or referral.

(idiomatic) Not gradually; all at once. Refers especially to quitting a habit by force of will rather than by a gradual reduction.

(pathology) A chronic abscess that forms slowly, without pain, heat or inflammation.

A sales call either by telephone or personal presence, made without a referral or without preparing the recipient of the call.

(law enforcement, slang) A criminal investigation that has not been solved after a considerable time but remains “on the books” and may be reopened when new evidence appears.

(idiomatic) In a ruthless and unfeeling manner, particularly as applied to first-degree murder committed without provocation and with malice aforethought.

(historical) The period of hostility short of open war between the Soviet Bloc and the Western powers, especially the United States, between 1945 and 1991.

A period of hostile relations between rivals where direct open warfare between them is largely undesired and avoided.

Sudden and complete withdrawal from a dependent substance, especially a drug. / The physiological effects of such a withdrawal.

(metallurgy) Of metal: brittle at low temperatures.