Origin and history of anti-trust

c. 1200, "reliance on the veracity, integrity, or other virtues or sound principles of someone or something; religious faith," probably from Old Norse traust "help, confidence, protection, support," from Proto-Germanic abstract noun *traustam (source also of Old Frisian trast, Dutch troost "comfort, consolation," Old High German trost "trust, fidelity," German Trost "comfort, consolation," Danish trøst, Gothic trausti "agreement, alliance").

This is reconstructed to be from Proto-Germanic *treuwaz, source of Old English treowian "to believe, trust," and treowe "faithful, trusty" (from PIE root *deru- "be firm, solid, steadfast;" compare trow (v.), true (adj.)).

It is attested from c. 1300 as "reliability, trustworthiness; trustiness, fidelity, faithfulness;" from late 14c. as "confident expectation" and "that on which one relies."

It is recorded from early 15c. in the legal sense of "confidence placed in a person who holds or enjoys the use of property entrusted to him by its legal owner;" and by mid-15c. as "condition of being legally entrusted," hence "that which is committed to one for safekeeping or use."

The meaning "businesses organized to reduce competition; an organization for the control of several corporations under one direction" by a set of majority shareholders in all of them, is a legal sense attested by 1877 which exploded as a U.S. political issue, hence trust-buster, recorded by 1903.

word-forming element of Greek origin meaning "against, opposed to, opposite of, instead," shortened to ant- before vowels and -h-, from Old French anti- and directly from Latin anti-, from Greek anti (prep.) "over, against, opposite; instead, in the place of; as good as; at the price of; for the sake of; compared with; in opposition to; in return; counter-," from PIE *anti "against," also "in front of, before" (from root *ant- "front, forehead," with derivatives meaning "in front of, before"), which became anti- in Italian (hence antipasto) and French.

It is cognate with Sanskrit anti "over, against," and Old English and- (the first element in answer). A common compounding element in Greek, in some combinations it became anth- for euphonic reasons. It appears in some words in Middle English but was not commonly used in English word formations until modern times. In a few English words (anticipate, antique) it represents Latin ante.

In noun compounds where it has the sense of "opposed to, opposite" (Antichrist, anti-communist) the accent remains on the anti-; in adjectives where it retains its old prepositional sense "against, opposed to," the accent remains on the other element (anti-Christian, anti-slavery).