Zepto-

//ˈzɛp.təʊ// prefix

prefix ·Rare ·Advanced level

Definitions

Prefix
  1. 1
    In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10⁻²¹ (short scale sextillionth or long scale trilliardth). Symbol: z morpheme

Antonyms

All antonyms

Etymology

Greek (h)epta- (seven), for the seventh order of 10⁻³. The final o conforms to the finals vowel of the SI series from micro- downwards; the letter z was added, as a start in a series of terms running backwards through the alphabet.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.