early 15c., "of or pertaining to tools and their use," from mechanic (adj.) + -al (1). By 1570s as "of or pertaining to machines and their use." Of persons or human actions, "resembling machines, automatic, lacking spirit or spontaneity," from c. 1600. Scientific sense of "of or pertaining to the material forces of nature acting on inanimate bodies," from 1620s. Related: Mechanically. Mechanical-minded is recorded from 1820.
late 14c., of a craft or skill, "pertaining to or involving mechanical labor" (a sense now usually with mechanical), also "having to do with tools," from Latin mechanicus "of or belonging to machines or mechanics; inventive," from Greek mēkhanikos "full of resources, inventive, ingenious," literally "mechanical, pertaining to machines," from mēkhanē "device, tool" (see machine (n.)). Meaning "of the nature of or pertaining to machines" is from 1620s.
early 14c., "one who cuts grass with a scythe," agent noun from mow (v.). Mechanical sense is from 1852.