epiglottis n.

before vowels reduced to ep-, before aspirated vowels eph-, word-forming element meaning "on, upon, above," also "in addition to; toward, among," from Greek epi "upon, at, close upon (in space or time), on the occasion of, in addition," also "after," from PIE *epi, *opi "near, at, against" (source also of Sanskrit api "also, besides;" Avestan aipi "also, to, toward;" Armenian ev "also, and;" Latin ob "toward, against, in the way of;" Oscan op, Greek opi- "behind;" Hittite appizzis "younger;" Lithuanian ap- "about, near;" Old Church Slavonic ob "on"). A productive prefix in Greek; also used in modern scientific compounds (such as epicenter).

"word inserted as an explanation, translation, or definition," c. 1300, glose (modern form from 1540s; earlier also gloze), from Late Latin glossa "obsolete or foreign word," one that requires explanation; later extended to the explanation itself, from Greek glōssa (Ionic), glōtta (Attic) "language, a tongue; word of mouth, hearsay," also "obscure or foreign word, language," also "mouthpiece," literally "the tongue" (as the organ of speech), from PIE *glogh- "thorn, point, that which is projected" (source also of Old Church Slavonic glogu "thorn," Greek glokhis "barb of an arrow").

Glosses were common in the Middle Ages, usually rendering Hebrew, Greek, or Latin words into vernacular Germanic, Celtic, or Romanic. Originally written between the lines, later in the margins. By early 14c. in a bad sense, "deceitful explanation, commentary that disguises or shifts meaning." This sense probably has been colored by gloss (n.1). Both glossology (1716) and glottology (1841) have been used in the sense "science of language."