1801, "one of the pieces with which the game of dominoes is played," from French domino (1771), perhaps (on a perceived resemblance to the black tiles of the game) from the earlier meaning "hood with a cloak worn by canons or priests over other vestments in cold weather" (1690s in English), from Latin dominus "lord, master" (from domus "house," from PIE root *dem- "house, household"), but the connection is not clear.
Metaphoric use in geopolitics dates to 1953, when U.S. President Eisenhower used the image in reference to what happens when you set dominoes upright in a row and knock the first one down. It came to be known as the domino theory.
President Eisenhower, on August 4, 1953, explained that if Indonesia fell, "the peninsula, the last little bit of land hanging on down there, would be scarcely defensible." "All India," he continued, "would be outflanked," and "Burma would be in no position for defense. On April 7, 1954, the President was still warning that if Indochina fell, all of southeast Asia would collapse like "falling dominoes." The President said, that as the last domino in the line falls inevitably from the toppling of the first, the loss of Indochina would lead to the loss of Burma, of Thailand, and Indonesia, and a threat to Australia and New Zealand. [Rep. Joseph R. McCarthy, Congressional Record, Aug. 2, 1955]
mid-14c., "execution or completion (of an act)," from Old French efet (13c., Modern French effet) "result, execution, completion, ending," from Latin effectus "accomplishment, performance," from past participle stem of efficere "work out, accomplish," from assimilated form of ex "out" (see ex-) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put"). From French, borrowed into Dutch, German, Scandinavian.
From late 14c. as "power or capacity to produce an intended result; efficacy, effectiveness," and in astrology, "operation or action (of a heavenly body) on human affairs; influence." Also "that which follows from something else; a consequence, a result." From early 15c. as "intended result, purpose, object, intent." Also formerly with a sense of "reality, fact," hence in effect (late 14c.), originally "in fact, actually, really." Meaning "impression produced on the beholder" is from 1736. Sense in stage effect, sound effect, etc. first recorded 1881.
"to produce as a result; to bring to a desired end," 1580s, from Latin effectus, past participle of efficere "work out, accomplish" (see effect (n.)). Related: Effecting; effection; effectible.
early 13c., name given to the rite of Vespers of the Office of the Dead, so called from the opening of the first antiphon, "I will please the Lord in the land of the living" (Psalms cxvi.9, in Vulgate Placebo Domino in regione vivorum), from Latin placebo "I shall please," future indicative of placere "to please" (see please).
Medical sense is recorded by 1785, "a medicine given more to please than to benefit the patient." Placebo effect is attested from 1900.
"game regularly played with 28 flat, oblong pieces, black on one side, spotted black and white on the other," c. 1800; see domino.
"producing an effect; having power to produce an effect," late 14c., Old French effectuel, from Late Latin effectualis, from Latin effectus "accomplishment, performance" (see effect (n.)). Used properly of actions (not agents) and with a sense "having the effect aimed at" (effective, by contrast, is used of the agent or the thing done and with a sense "having great effect"). Related: Effectually; effectualness.
late 14c., "serving to effect the intended purpose," from Old French effectif, from Latin effectivus "productive, effective," from effect-, stem of efficere "work out, accomplish" (see effect (n.)). Of military forces, "fit for action or duty," from 1680s.
late 14c., "card, die, or domino with three spots," from Anglo-French, Old French treis (Modern French trois), oblique case of treie "three," from Latin tria (neuter) "three" (see three). In slang use for "three (of anything)" from 1887.