nano-

WordReference Random House Unabridged Dictionary of American English © 2025

nano-, 

1. a combining form with the meaning "very small, minute,'' used in the formation of compound words (nanoplankton);
   in the names of units of measure it has the specific sense "one billionth'' (10^-9): nanomole;
   nanosecond. Also, nanno-;
   esp. before a vowel, nan-.

Also, nanno-;
esp. before a vowel, nan-.

• combining form representing Greek nânos, nánnos dwarf 

Collins Concise English Dictionary © HarperCollins Publishers::

nano- combining_form

1. denoting 10^–9: nanosecond
   Symbol: n

Etymology: from Latin nānus dwarf, from Greek nanos