yocto-

/ˈjɑk.toʊ/

UK: /ˈjɒk.təʊ/

JⱭK · 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 10⁻²⁴ short scale septillionth or long scale quadrillionth).

Etymology

Ancient Greek ὀκτώ (oktṓ, “eight”), for the eighth order of 10⁻³. The letter y was added, as the second term in a series running backwards through the alphabet.