/ ˈmaɪkrəʊ; NAmE -kroʊ/ combining form
1.
(in nouns, adjectives and adverbs) small; on a small scale :
microchip
microorganism
OPP macro-
2.
(in nouns; used in units of measurement) one millionth :
a microlitre
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WORD ORIGIN
from Greek mikros small.