Definition of nano- in US English:

nano-

combining form

  • 1Denoting a factor of 10⁻⁹ (used commonly in units of measurement)

    ‘nanosecond’
    1. 1.1 Denoting a very small item.
      ‘nanoplankton’

Origin

Via Latin from Greek nanos ‘dwarf’.

Pronunciation

nano-

/ˈnænoʊ//ˈnanō/