pre-empt (v.)youdaoicibaDictYouDict[pre-empt 词源字典]
also preempt, 1830, "secure by pre-emtion," back-formation from pre-emption, originally American English. In the broascasting sense, it is attested from 1965, American English, a euphemism for "cancel." Related: pre-empted; preempted. [pre-empt etymology, pre-empt origin, 英语词源]
pre-emption (n.)youdaoicibaDictYouDict
also preemption, c. 1600, literally "the right of purchasing before others," from pre- "before" + emption.
pre-emptive (adj.)youdaoicibaDictYouDict
also preemptive, 1806, "pertaining to preemption;" from pre-emption + -ive. Specifically of an attack on an enemy who is plotting his own attack, 1958, a term from the Cold War. Related: Pre-emptively; preemptively.
pre-emptory (adj.)youdaoicibaDictYouDict
also preemptory, 1822, "relating to pre-emption," from pre-emption + -ory.