(plural

testes

), 1704, from Latin

testis

"testicle," usually regarded as a special application of

testis

"witness" (see

testament

), presumably because it "bears witness to male virility" [Barnhart]. Stories that trace the use of the Latin word to some supposed swearing-in ceremony are modern and groundless.Compare Greek

parastatai

"testicles," from

parastates

"one that stands by;" and French slang

témoins

, literally "witnesses." But Buck thinks Greek

parastatai

"testicles" has been wrongly associated with the legal sense of

parastates

"supporter, defender" and suggests instead

parastatai

in the sense of twin "supporting pillars, props of a mast," etc. Or it might be a euphemistic use of the word in the sense "comrades." OED, meanwhile, points to Walde's suggestion of a connection between

testis

and

testa

"pot, shell, etc." (see

tete

).