mid-14c., "net to catch fish" (implied in trammeller "one who fishes with a trammel net"), from Old French tramail "fine-gauged fishnet" (13c.), from Late Latin tremaculum, perhaps meaning "a net made from three layers of meshes," from Latin tri- "three" (see tri-) + macula "a mesh" (see mail, n.2). Meaning "anything that hinders" is from 1650s, originally "a hobble for a horse" (c.1500). Italian tramaglio, Spanish trasmallo are French loan-words.

1530s, originally "to bind up (a corpse);" sense of "hinder, restrain" is from 1727, from trammel, n., a figurative use from the literal sense "bind (a horse's legs) with a trammel" (c.1600). Related: Trammeled; trammeling.