To comment at length; discourse: "He used to descant critically on the dishes which had been at table"(James Boswell).
also dis·cant (dĭs'kānt', dĭ-skānt') Music
To sing or play a descant.
To sing melodiously.
[Middle English, from Anglo-Norman descaunt, from Medieval Latin discantus, a refrain : Latin dis-, dis- + Latin cantus, song, from past participle of canere, to sing; see kan- in Indo-European roots.] des'cant'er n.
c.1380, from Anglo-Fr. deschaunt, from M.L. discantus "refrain, part-song," from L. dis- "asunder, apart" + cantus "song." Spelling was partly Latinized 16c. Originally "counterpoint;" sense of "talk at length" is first attested 1649.