A trump is a playing card which is elevated above its usual rank in trick-taking games. Typically, an entire suit is nominated as a trump suit; these cards then outrank all cards of plain (non-trump) suits. In other contexts, the term trump card can refer to any sort of action, authority, or policy which automatically prevails over all others.
The English word derives from trionfi, a type of 15th-century Italian playing cards, from the Latin "triumph, victory procession", ultimately (via Etruscan) from Greek θρίαμβος, the term for a hymn to Dionysus sung in processions in his honour.
Trionfi was the 15th-century card game for which tarot cards were designed. Trionfi were a fifth suit in the card game which acted as permanent trumps. Still in the 15th century, the French game triomphe (Spanish triunfo) used four suits one of which was randomly selected as trumps. It was this game that became extremely popular in Western Europe in the 16th century and is ancestral to many modern card games.
The English word is first documented in 1529 as the name of a card game which would develop into Ruff and Honours and ultimately Whist. In German, the term is attested as Triumph in 1541; the modern German spelling Trumpf is recorded from 1590. In French, triomphe remained the name of the game, while the trump suit was called , from à tout (as it were ""). Some European languages (Hungarian, Greek) adopted the French term. Russian козырь kozyr' is of unknown etymology, possibly a loan from a Turkic source. Polish variously uses atut, trumf and kozer adopted from the French, German and Russian respectively.
In most games, the relative rank of cards within a suit is the same in trump and plain suits, but they may sometimes differ, for example in Klabberjass, Euchre, or Eighty Points.