Definition of "elfin"

elfin¹

/ˈɛlfɪn/

noun
plural elfins
1. An elf; an inhabitant of fairy-land.
2. A little urchin or child.
3. Any of the butterflies in the subgenus Incisalia of the North American lycaenid genus Callophrys.

elfin²

/ˈɛlfɪn/

adjective
comparative more elfin, superlative most elfin
1. Relating to or resembling an elf or elves, especially in its tiny size or features.
  Quotations
  Three chairs of the steamer type, all maimed, comprised the furniture of this roof-garden, with […] on one of the copings a row of four red clay flower-pots filled with sun-baked dust from which gnarled and rusty stalks thrust themselves up like withered elfin limbs.
  1914, Louis Joseph Vance, “Anarchy”, in Nobody, New York, N.Y.: George H[enry] Doran Company, published 1915, page 33
  He’s forced to travel back to 1969 to prevent an evil alien (a shockingly effective, nearly unrecognizable Jemaine Clement of Flight Of The Conchords, playing sort of a psychotic extraterrestrial-biker serial killer) from destroying the world by killing Brolin. Smith is aided in his quest by an elfin, time-jumping alien with psychic powers played by another Coen brothers veteran, A Serious Man star Michael Stuhlbarg.
  2012 May 24, Nathan Rabin, “Film: Reviews: Men In Black 3”, in The Onion AV Club