1845, introduced by John Lindley in the third edition of "School Botany," from Modern Latin Orchideæ (Linnaeus), the plant's family name, from Latin orchis, a kind of orchid, from Greek orkhis (genitive orkheos) "orchid," literally "testicle," from PIE *h(o)rghi-, the standard Indo-European word for "testicle" (source also of Avestan erezi, Armenian orjik'"testicles," Old Irish uirge, Hittite arki- "testicle," Lithuanian eržilas "stallion").

The plant so called because of the shape of its root; Greek orkhis also was the name of a kind of olive, also so called for its shape. Earlier in English in Latin form, orchis (1560s), and in Middle English it was ballockwort (c. 1300; see ballocks). The modern word is marred by an extraneous -d- in an attempt to extract the Latin stem. Related: Orchidaceous.

"courage," literally "testicles, balls," 1932, in Hemingway ("Death in the Afternoon," an account of Spanish bull-fighting), from Spanish cojon "testicle," from Latin coleus "the testicles" (source of Italian coglione), literally "strainer bag," a variant of culleus "a leather sack," cognate with Greek koleos "sheath of a sword, scabbard." Both are said in some sources to be from PIE root *kel- (1) "to cover, conceal, save," but de Vaan finds it "Probably a loanword from a non-IE language, independently into Latin and Greek."

English had it as cullion a 16c. term of contempt for a man, "a mean wretch" (Shakespeare) also "a testicle" (Chaucer), from Middle English coujon, coilon (late 14c.), from Old French coillon "testicle; worthless fellow, dolt," from Latin coleus. 

type of cephalopod, 1590s, earlier simply cuttle, from Old English cudele "the cuttlefish;" first element perhaps related to Middle Low German küdel "container, pocket;" Old Norse koddi "cushion, testicle;" and Old English codd (see cod). In 17c. sometimes scuttlefish.

"a cutting out of one or both of the testicles," 1870, from Latinized form of Greek orkhis "testicle" (see orchid) + -ectomy "a cutting, surgical removal." Coined by medical men in an attempt to avoid the common word castration.

1690s, earlier cully (1660s) "a dupe, a sap-head," "a verdant fellow who is easily deceived, tricked, or imposed on" [Century Dictionary], rogues' slang, of uncertain origin.

Perhaps a shortening of cullion "base fellow," originally "testicle" (from French couillon, from Old French coillon "testicle; worthless fellow, dolt," from Latin coleus, literally "strainer bag;" see cojones). Another theory traces it to Romany (Gypsy) chulai "man." Also sometimes in the form cully, however some authorities assert cully was the canting term for "dupe" and cull was generic "man, fellow" without implication of gullibility. Compare also gullible. Related: Cullibility (1728).