a list of terms in a special subject, field, or area of usage, with accompanying definitions.
2.
such a list at the back of a book, explaining or defining difficult or unusual words and expressions used in the text.
Origin: 1350–1400; Middle English glossarye < Latin glōssarium difficult word requiring explanation < Greek glōssárion, diminutive of glôssa tongue, language; later taken as a collection of such words, by construing suffix as Latin -ārium-ary; compare gloss2