noun
1Biology
A middle section or part of a structure, organism, etc.2Biology
A region of the spermatozoon located behind the neck and ensheathed in closely-packed mitochondria.3Medicine
historical A component of complement identified in the euglobulin fraction (consisting chiefly of the first component, C1).
Origin
Late 19th century; earliest use found in American Naturalist. From mid + piece.
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