microyoudaoicibaDictYouDict[micro 词源字典]
micro: [19] The conversion of the prefix microinto a noun (standing, for instance, for a microskirt or microcomputer) is not as recent as one might have supposed: as long ago as the 1860s it was being used for a sort of tiny moth (short for microlepidoptera). The prefix itself comes from Greek mīkrós ‘small’, a variant of smīkrós, which may be distantly related to English small.

The earliest English word containing it appears to have been microcosm [15], etymologically ‘little world’. From the 17th century come micrometer, microphone, and microscope. Microbe [19] means etymologically ‘little life’ (from Greek bíos ‘life’), hence ‘little creature’.
[micro etymology, micro origin, 英语词源]