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- .
[ comb. form repr. Gk nânos, nánnos dwarf ]