1. Combining form meaning large, oversize; opposite of micro-. SEE ALSO: macro-, megalo-. 2. (M) Prefix used in the SI and metric system to signify multiples of one million (106). [G. megas, big]
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prefix denoting
1. large size, or abnormal enlargement or distension. Example: megacaecum (of the caecum).
2. a million. Example: megavolt (a million volts).
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[Gr. megas big, great] a prefix (a) meaning large, enlarged, or of abnormally large size; see also words beginning megal(o)-, and (b) used in naming units of measurement to indicate a quantity one million (106) times the unit designated by the root with which it is combined (symbol M).Medical dictionary. 2011.