accentuate (v.) 1731, "pronounce with an accent," from Medieval Latin accentuatus, past participle of accentuare "to accent," from Latin accentus "song added to speech," from ad "to" (see ad-) + cantus "a singing," past participle of canere "to sing" (from PIE root *kan- "to sing"). Figurative meaning "emphasize, place an accent or emphasis on" is recorded from 1865.
late 14c., "particular mode of pronunciation," from Old French acent "accent" (13c.), from Latin accentus "song added to speech," from ad "to" (see ad-) + cantus "a singing," past participle of canere "to sing" (from PIE root *kan- "to sing"). The Latin word was a loan-translation of Greek prosōidia, from pros- "to" + ōidē "song," which apparently described the pitch scheme in Greek verse. The meaning "effort in utterance making one syllable stronger than another in pitch or stress" is attested from 1580s; as "mark or character used in writing to indicate accent," it is recorded by 1590s. The decorative-arts sense of "something that emphasizes or highlights" is from 1972.The soundest distinction perhaps is that "accent" refers to the habitual stress laid on a syllable in ordinary pronunciation ; "stress" to a syllable specially accented for this or that reason, logical, rhetorical, or prosodic purely. [George Saintsbury, "Historical Manual of English Prosody," 1914]
1520s, "hasten the occurrence of;" 1590s, "make quicker" (implied in accelerating), from Latin acceleratus, past participle of accelerare "to hasten, quicken" (trans.), "make haste" (intrans.), from ad "to" (see ad-) + celerare "hasten," from celer "swift," which is perhaps from PIE *keli- "speeding" (see celerity). The intransitive sense of "go faster, become faster" in English is from 1640s. Related: Accelerated; accelerative.
"act or condition of going faster," 1530s, from Latin accelerationem (nominative acceleratio) "a hastening," noun of action from past-participle stem of accelerare "to hasten, quicken," from ad "to" (see ad-) + celerare "hasten," from celer "swift," which is perhaps from PIE *keli- "speeding" (see celerity).
"come to or arrive at" (a state, position, office, etc.), early 15c., from Latin accedere "approach, go to, come near, enter upon," from assimilated form of ad "to" (see ad-) + cedere "go, move, withdraw" (from PIE root *ked- "to go, yield"). Latin ad- usually became ac- before "k" sounds. Related: Acceded; acceding.
1868, earlier alla capella (1824), from Italian, "in the style of Church music, in the manner of the chapel," literally "according to the chapel," from cappella "chapel" (see chapel). Originally in reference to older church music (pre-1600) which was written for unaccompanied voices; applied 20c. to unaccompanied vocal music generally. Italian a is from Latin ad "to, toward; for; according to" (see ad-); alla is a la "to the." Sometimes in the Latin form a capella. Also denoting "that instruments are to play in unison with the voices, or that one part is to be played by a number instruments." ["Chambers's Encyclopaedia," 1868]You are not the first person puzzled by the expression "A Capella," or, at any rate, unable to understand it should signify the exact reverse of what it literally does signify. The chorales in oratorios were invariably accompanied, either by double-bass or the whole band. Hence they were, with perfect correctness, said to be performed "a capella." But, as other chorales, sung as part of the church service, were written in the same and simple style the expression "a capella" came in time to be applied to them also, despite their being sung without any instrumental accompaniment whatever. [The Music World, Sept. 11, 1875]