Definition of magic word in US English:

magic word

noun

  • 1A word supposed to produce effects by magic; (in plural) the words comprising an incantation or spell.

  • 2Any word or (in plural) phrase regarded as imbued with some special significance, or as having a pronounced or remarkable effect like that of magic (especially ‘please’); (frequently) one which permits or otherwise influences a specific action or event.

Origin

Late 16th century; earliest use found in John Studley (c1545–?1590), translator.