module (n.)

1580s, "allotted measure," a sense now obsolete, from Middle French module (1540s) or directly from Latin modulus "small measure," diminutive of modus "measure, manner" (from PIE root *med- "take appropriate measures"). Sense of "a standard measure to regulate proportions" is from 1620s. Meaning "interchangeable part" is recorded by 1955, via the notion of "length chosen as the basis for the dimensions of parts of a building, etc." (1936); that of "separate section of a spacecraft" is from 1961.