chord n.1

c. 1300, corde, "a string or small rope composed of several strands twisted or woven together; bowstring, hangman's rope," from Old French corde "rope, string, twist, cord," from Latin chorda "string of a musical instrument, cat-gut," from Greek khorde "string, catgut, chord, cord," from PIE root *ghere- "intestine."

Also from c. 1300 as "string of a musical instrument." From c. 1400 as "a tendon or muscle." Figurative sense of "anything which binds or restrains" is from late 14c. Meaning "raised, cord-like rib on the surface of cloth" is from 1776. As a measure of wood of 128 cubic feet (eight feet long, four feet high and wide) first recorded 1610s, so called because it was measured with a cord of rope.

*gherə-, Proto-Indo-European root meaning "gut, entrail." 

It forms all or part of: Chordata; chordate; chord (n.2) "structure in animals resembling a string;" chorion; cord; cordon; harpsichord; haruspex; hernia; notochord; yarn.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit hira "vein; band;" Latin hernia "rupture;" Greek khorde "intestine, gut-string;" Lithuanian žarna "guts, leather bag;" Old English gearn, Old High German garn "yarn" (originally made of dried gut), Old Norse gorn "gut."