denoting a mode or melody in Gregorian music in which the final is in the middle of the compass instead of at the bottom, 1590s, from Medieval Latin plagalis, from plaga "the plagal mode," probably from plagius, from Medieval Greek plagios "plagal," in classical Greek "oblique," from plagos "side" (from PIE root *plak- (1) "to be flat").

"short song or poem intended to be sung to a simple melody,"early 14c., from Old French ditie "composition, poem, treatise," from Latin dictatum "thing dictated," neuter past participle of dictare "dictate," frequentative of dicere "to say, speak" (from PIE root *deik- "to show," also "pronounce solemnly"). In Middle English used of any literary composition, including dramas, essays, letters.

"melody for a single voice," 1775, from Italian aria, literally "air" (see air (n.1)).

Historically considered, the aria marks a single moment in the course of a dramatic action. The text often consists of but a few words, many times repeated (as we find in Handel's oratorios, etc.), and the musical development is the main thing. The opposite of aria is recitative (q.v.), in which the declamation of the syllables is the main thing, colored, perhaps, by means of clever orchestration. [W.S.B. Mathews and Emil Liebling, "Dictionary of Music," 1896]

type of Afro-Cuban dance, also a ballroom dance based on it, the rhythm of it, and the music suitable for it; 1914 ("La Rumba" was the name of a popular tango melody from 1913), from Cuban Spanish rumba, originally "spree, carousal," derived from Spanish rumbo "spree, party," earlier "ostentation, pomp, leadership," perhaps originally "the course of a ship," from rombo "rhombus," in reference to the compass, which is marked with a rhombus. The verb is recorded from 1932. Related: Rumbaed; rumbaing.

1570s, "full of corn, pertaining to corn," from corn (n.1) + -y (2). Chaucer used it of ale (late 14c.), perhaps to mean "malty." American English slang "old-fashioned, sentimental" is from 1932 (first attested in "Melody Maker"), perhaps originally "something appealing to country folk" (corn-fed in the same sense is attested from 1929). Related: Cornily; corniness.

There's an element of truth in every idea that lasts long enough to be called corny. [songwriter Irving Berlin (1888-1989), in a 1962 interview]

late 14c., modulacioun, "act of singing or making music, harmony," from Old French modulation "act of making music" (14c.) and directly from Latin modulationem (nominative modulatio) "rhythmical measure, singing and playing, melody," noun of action from past-participle stem of modulari "regulate, measure off properly, measure rhythmically; play, play upon," from modulus "small measure," diminutive of modus "measure, manner" (from PIE root *med- "take appropriate measures"). Meaning "act of regulating according to measure or proportion" is from 1530s. Musical sense of "action or process of changing from one key to another" is by 1690s.