a Greek word used in various senses in English; from Greek prothesis "a putting, a placing before, a placing in public," from pro "before" (see pro-) + thesis "a placing" (from reduplicated form of PIE root *dhe- "to set, put"). In the ecclesiastical sense ("preparation of the eucharistic elements before the liturgy in the Greek Church") from 1670s; grammatical sense ("addition of one or more sounds or letters at the beginning of a word") is by 1870. Related: Prothetic (1835 in grammar); prothetical; prothetically.

abnormal number of chromosomes, 1934, from adjective aneuploid (1931), Modern Latin, coined 1922 by G. Täckholm from Greek an- "not, without" (see an- (1)) + euploid, from Greek eu "well, good" (see eu-) + -ploid, from -ploos "fold" (from PIE root *pel- (2) "to fold").

son of Agamemnon and Clytaemnestra, from Greek Orestes, literally "mountaineer," from oros "mountain" (see oread).

"a philanthropist," 1734, from Latin philanthropos, from Greek philanthrōpos "loving mankind, humane" (see philanthropy).

"of or of the nature of a virgin," 1834, from Greek parthenikos, from parthenos "virgin," a word of unknown origin.

c. 1600, in reference to Greek music, from Late Latin enharmonicus, from Greek enharmonikos, from en (see en- (2)) + harmonikos (see harmonic). From 1794 in reference to a modern music note that can be indicated in different ways (G sharp/A flat).

before vowels kary-, word-forming element used since c. 1874 in biological terms referring to cell nuclei, from Greek karyon "nut, kernel," possibly from PIE root *kar- "hard," but Beekes leans toward the notion that it is a Pre-Greek word.

before vowels oct-, word-forming element meaning "eight," from Greek okta-, okt-, from PIE *okto(u) "eight" (see eight). The variant form octo- often appears in words taken from Latin, but the Greek form is said to be the more common in English.

1640s, "noxious, poisonous," from Medieval Latin deleterius, from Greek dēlētērios "noxious," from dēlētēr "destroyer," from dēlēisthai "to hurt, injure," of which Beekes writes, "the verb is probably non-IE, i.e. Pre-Greek." From 1823 as "mentally or morally hurtful or injurious." Related: Deleteriously; deleteriousness.

"inflammation of a joint," 1540s, from medical Latin arthritis, from Greek (nosos) arthritis "(disease) of the joints," from arthritis, fem. of arthrites (adj.) "pertaining to joints" (Greek nosos is a fem. noun), from arthron "a joint" (from PIE root *ar- "to fit together"). The older noun form was arthetica (late 14c.).