crochet Look up crochet at Dictionary.com
1846, from Fr. crochet, dim. of croc "hook," from O.N. krokr "hook." So called for the hooked needle used.
crocket Look up crocket at Dictionary.com
c.1300, "curl of hair," from Anglo-Fr. crocket, northern Fr. form of Fr. crochet (see crochet). Meaning "ornamental device on a Gothic pediment" is from late 14c.
crotchet Look up crotchet at Dictionary.com
late 14c., "crocket," later "small hook" (early 15c.), from Fr. crochet "hook" (see crochet). As a surgical instrument, from 1750. Fig. use in musical notation is from mid-15c., from the shape of the notes. Meaning "whimsical fancy" is from 1570s; perhaps from the same mechanical image in crank; but other authorities link this sense to the musical notation one.
crotch Look up crotch at Dictionary.com
1530s, original meaning "pitchfork," from O.N.Fr. croche "shepherd's crook," var. of croc "hook" (see crochet); meaning "region where the body forks" is 1590s.