WordNet sense 1 (usually good-naturedly mischievous):

elfish, elvish

WordNet sense 2 (full of fun and high spirits):

playful

WordNet sense 3 (suggestive of an elf in strangeness and otherworldliness):

fey

WordNet sense 4 (not existing in nature or subject to explanation according to natural laws; not physical or material):

supernatural

WordNet sense 5 (small and delicate):

elflike

WordNet sense 6 (limited or below average in number or quantity or magnitude or extent):

little