zepto-

/ˈzɛp.toʊ/

UK: /ˈzɛp.təʊ/

ZƐP · toʊ (2 syllables)

English Prefix

Definition

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

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.