elf 
(ĕlf)
(ĕlf)n. pl. elves(ĕlvz)
1. A magical creature in human form but usually smaller, often considered mischievous.
2.
a. A lively, mischievous child.
b. A usually sprightly or mischievous or sometimes spiteful person.
[Middle English, from Old English ælf; see albho- in the Appendix of Indo-European roots.]