"cut wood sold by the cord for fuel," 1630s, from cord in the wood-measure sense + wood (n.).
Entries linking to cord-wood
cord n.
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.
wood n.
Old English wudu, earlier widu "tree, trees collectively, forest, grove; the substance of which trees are made," from Proto-Germanic *widu- (source also of Old Norse viðr, Danish and Swedish ved "tree, wood," Old High German witu "wood"), from PIE *widhu- "tree, wood" (source also of Welsh gwydd "trees," Gaelic fiodh- "wood, timber," Old Irish fid "tree, wood"). Out of the woods "safe" is from 1792.