demonstratorn.

Etymology: Originally < classical Latin dēmonstrātor person who points out or indicates, in post-classical Latin also person who proves or demonstrates (early 3rd cent. in Tertullian) < dēmonstrāt- , past participial stem of dēmonstrāre demonstrate v. + -or -or suffix. In later use probably also independently < demonstrate v. + -or suffix. Compare slightly earlier demonstrationer n. Foreign-language parallels. Compare Middle French demonstrateur , French démonstrateur (1499, originally in sense ‘person who demonstrates the truth of something’; rare before early 17th cent.; compare Old French demontrëor (end of the 12th cent.)), Old Occitan demostrador , Spanish demostrador (a1250), Portuguese demostrador (14th cent.; also demonstrador ), Italian dimostratore (a1342). With sense 2 compare Anglo-Norman demostrer , demostrour index finger (1213 or earlier as adjective, 14th cent. or earlier as noun). Historical variation in stress. The modern pronunciation with stress on the first syllable is recorded in dictionaries from at least the late 18th cent., e.g. in Sheridan (1780) and Smart (1836). In this period the word appears to have varied between stress on the first syllable, the second (or antepenultimate), and the third (or penultimate), and did not necessarily parallel the stress pattern shown by demonstrate v. Walker (1791) gives antepenultimate stress, commenting: ‘The accent on the penultimate syllable of this word seems appropriated to one whose office it is to demonstrate or exhibit any part of philosophy, when it merely means one who demonstrates any thing in general, the accent is on the same syllable as the verb’ (the ‘same syllable’ here being the second: see note at demonstrate v.). Most later editions of Walker (e.g. 1826, 1843) give only penultimate stress.