Origin and history of taper

Old English tapur, taper "candle, lamp-wick," not found outside English, possibly a specialized borrowing and dissimilation of Latin papyrus (see papyrus), which was used in Medieval Latin and some Romance languages for "wick of a candle" (such as Old Italian dialectal (Tuscany) papijo, papeio "wick"), because these often were made from the pith of papyrus. Compare also German kerze "candle," from Old High German charza, from Latin charta, from Greek khartēs "papyrus, roll made from papyrus, wick made from pith of papyrus."

Later especially a slender candle, usually of wax. The general sense of "a tapering form, gradual diminishing of thickness" is by 1793, from the verb.

1580s, "shoot up like a flame or spire," via an obsolete adjective taper (late 15c.) from taper (n.), on the notion of the converging form of the flame of a candle or (less likely) the candle itself. Also compare taper-wise (adv.) "conically" (mid-15c.).

The sense of "become slender, diminish" is attested by c. 1600. By 1789 as "gradually grow less in amount, force, etc." The transitive sense of "make gradually smaller" is from 1670s. To taper off "stop steadily or by degrees" is by 1848. Related: Tapered; tapering. Middle English agent noun taperer (n.) was ecclesiastical and meant "a candle-bearer, acolyte."