pref. 毫微

[计] 纳

[医] 矮, 小; 纤, 毫微

nano- \nan"o-\ (n[a^]n"[-o]-), pref.
1. A prefix meaning one-billionth; as, a nanogram is
one-thousandth of a microgram.
[PJC]

2. Very small; submicroscopic; -- used to designate sizes
smaller than those that would be referred to as {micro-};
as, nanoscale manipulations.
[PJC]