What is the meaning of the word moths?

Mothra is a fictional character, an outsized giant Moth or Butterfly that has both monster and benevolent roles. There is an important subplot involving kidnapped miniature Girls who are twins. The plot idea is something similar to Thumbellina with some added Nippon Monster touches. Mothra is shown in both the larval ( caterpillar, but looks like a giant slug, and Butterfly or Moth forms. One of the more intelligent( odd as this sounds) of the Japanese Monster epics.-It has some human interest, unlike a good many of them.