ラテン語のplus, more, greaterから、PIE*pele, to fill, to fill upから、語源的にはfill, fullと同じ。数学の名詞plusに使われ、利点、強さを意味する単語の派生。
英語の語源
plus (n.)
1570s, the oral rendering of the arithmetical sign +, from Latin plus "more, in greater number, more often" (comparative of multus "much"), altered (by influence of minus) from *pleos, from PIE *pele- (1) "to fill" (see poly-).
As a preposition, between two numbers to indicate addition, from 1660s. [Barnhart writes that this sense "did not exist in Latin and probably originated in commercial language of the Middle Ages."] Placed after a whole number to indicate "and a little more," it is attested from 1902. As a conjunction, "and," it is American English colloquial, attested from 1968. As a noun meaning "an advantage" from 1791. Plus fours (1921) were four inches longer in the leg than standard knickerbockers, to produce an overhang, originally a style associated with golfers. The plus sign itself has been well-known since at least late 15c. and is perhaps an abbreviation of Latin et (see et cetera).
例文
1. Three plus six makes nine.
3プラス6は9.（注意、この文の plus は前置詞で、plussixは前置詞句で、threeの定語を作るので、動詞はmakesで、makeを使わない）。
2.There are only 35 staff to serve 30000- plus customers.
従業員は35人しかいないのに、3万人以上の顧客にサービスを提供しなければならない。
3.All vessels were to be built on a cost- plus basis.
すべての船はコストプラス利益の上で製造されます。
4.Experience of any career in sales is a big plus .
どの販売分野での経験も大きな利点です。
5. Send a cheque for ￡18.99 plus ￡2 for postage and packing.