We found one dictionary that defines the word ultramicrosize:

General (1 matching dictionary)

1. ultramicrosize: Wiktionary

Definitions from Wiktionary (ultramicrosize) ▸ adjective:  Smaller than microsize. ▸ Words similar to ultramicrosize ▸ Usage examples for ultramicrosize ▸ Idioms related to ultramicrosize ▸ Wikipedia articles (New!) ▸ Popular nouns described by ultramicrosize ▸ Words that often appear near ultramicrosize ▸ Rhymes of ultramicrosize ▸ Invented words related to ultramicrosize