elves

(noun) an acronym for emissions of light and very low frequency perturbations due to electromagnetic pulse sources; extremely bright extremely short (less than a msec) electrical flashes forming a huge ring (up to 400 km diameter) in the ionosphere.

(noun) (folklore) fairies that are somewhat mischievous. Synonyms: elf, hob, gremlin, pixie, pixy, brownie, imp.

(noun) below 3 kilohertz. Synonyms: extremely low frequency, ELF.