extension (n.)

c. 1400, "a swelling, a bulging," from Latin extensionem/extentionem (nominative extensio/extentio) "a stretching out, extension," noun of action from past-participle stem of extendere (see extend). In a concrete sense, "extended portion of something" (a railroad, etc.), from 1852. The telephone sense is from 1906.

updated on January 29, 2023