twice

英文词源

twice

twice: [12] Twice was formed from Old English twige ‘twice’ (itself based on twi-, the combining form of two) and the genitive ending -s, which was used for creating adverbs, such as always, nowadays, once, thrice, etc.
=> two

twice (adv.)

late Old English twies, from Old English twiga, twigea "two times," from Proto-Germanic *twiyes (cognates: Old Frisian twia, Old Saxon tuuio), from PIE *dwis-, adverbial form of *dwo- "two" (see two). Spelling with -ce reflects the voiceless pronunciation.

Life is as tedious as a twice-told tale
Vexing the dull ear of a drowsy man.
["King John," III.iv.]

Think twice, then speak was an "old Prouerbe" by 1623. At twice, though less common than at once, means "at two distinct times; by two distinct operations."