two-to-the-N
= U =
UBD
u- pref.
Written shorthand for micro-; techspeak when
applied to metric units, jargon when used otherwise. Derived from
the Greek letter
"mu",
the first letter of "micro" (and which
letter looks a lot like the English letter "u").
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.