bias Look up bias at Dictionary.com
1520s, from Fr. biais "slant, oblique," also figuratively, "expedient, means" (13c., in O.Fr. "sideways, askance, against the grain"), from O.Prov. biais, with cognates in Old Catalan and Sardinian; possibly from V.L. *(e)bigassius, from Gk. epikarsios "athwart, crosswise, at an angle," from epi- "upon" + karsios "oblique," from PIE *krs-yo-, from base *(s)ker- "to cut." A pp. adjective that became a noun in Old French. Transferred sense of "predisposition, prejudice" is from 1570s.
"[A] technical term in the game of bowls, whence come all the later uses of the word." [OED]
The verb is from 1620s.