1. [n]  below 3 kilohertz
2. [n]  (folklore) fairies that are somewhat mischievous

Elf
Elf

more details ...

1. \Elf\ ([e^]lf), n.; pl. {Elves} ([e^]lvz). [AS. [ae]lf, ylf;
   akin to MHG. alp, G. alp nightmare, incubus, Icel. [=a]lfr
   elf, Sw. alf, elfva; cf. Skr. [.r]bhu skillful, artful, rabh
   to grasp. Cf. {Auf}, {Oaf}.]
   1. An imaginary supernatural being, commonly a little sprite,
      much like a fairy; a mythological diminutive spirit,
      supposed to haunt hills and wild places, and generally
      represented as delighting in mischievous tricks.
            Every elf, and fairy sprite, Hop as light as bird
            from brier.                           --Shak.
   2. A very diminutive person; a dwarf.
   {Elf arrow}, a flint arrowhead; -- so called by the English
      rural folk who often find these objects of prehistoric
      make in the fields and formerly attributed them to
      fairies; -- called also {elf bolt}, {elf dart}, and {elf
      shot}.
   {Elf child}, a child supposed to be left by elves, in room of
      one they had stolen. See {Changeling}.
   {Elf fire}, the ignis fatuus. --Brewer.
   {Elf owl} (Zo["o]l.), a small owl ({Micrathene Whitneyi}) of
      Southern California and Arizona.
   

2. \Elf\, v. t.
   To entangle mischievously, as an elf might do.
         Elf all my hair in knots.                --Shak.
   

Binary format used by System V Release 4 Unix.