descant

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Music An ornamental melody or counterpoint sung or played above a theme.
2. n. Music The highest part sung in part music.
3. n. A discussion or discourse on a theme.
4. v. To comment at length; discourse: "He used to descant critically on the dishes which had been at table” ( James Boswell).
5. v. Music To sing or play a descant.
6. v. Music To sing melodiously.

Century Dictionary and Cyclopedia

1. n. In music: A counterpoint added to a given melody or cantus firmus, and usually written above it.
2. n. The art of contriving such a counterpoint, or, in general, of composing part-music. Descant was the first stage in the development of counterpoint; it began about 1100.
3. n. In part-music, the upper part or voice, especially the soprano or air.
4. n. A varied song; a song or tune with various modulations.
5. n. A continued discourse or series of comments upon a subject; a disquisition; comment; remark.
6. In music, to run a division or variety with the voice, on a musical ground in true measure; sing.
7. To make copious and varied comments; discourse; remark again and again in varied phrase; enlarge or dwell on a matter in a variety of remarks or comments about it: usually with on or upon before the subject of remark: as, to descant upon the beauties of a scene, or the shortness of life.

Wiktionary

1. n. A lengthy discourse on a subject
2. n. music a counterpoint melody sung or played above the theme
3. v. intransitive To discuss at length.
4. v. intransitive To sing or play a descant.

GNU Webster's 1913

1. n. Originally, a double song; a melody or counterpoint sung above the plain song of the tenor; a variation of an air; a variation by ornament of the main subject or plain song.
2. n. The upper voice in part music.
3. n. The canto, cantus, or soprano voice; the treble.
4. n. A discourse formed on its theme, like variations on a musical air; a comment or comments.
5. v. To sing a variation or accomplishment.
6. v. To comment freely; to discourse with fullness and particularity; to discourse at large.

WordNet 3.0

1. v. sing by changing register; sing by yodeling
2. v. talk at great length about something of one's interest
3. v. sing in descant
4. n. a decorative musical accompaniment (often improvised) added above a basic melody