Elves and Naiads

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.

Naiads and elves are semantically related. In some cases you can use "Naiads" instead a noun "Elves".

Elves and naiads are semantically related. Sometimes you can use "Elves" instead a noun "Naiads".