Online Etymology Dictionary

metrical: "pertaining to versification," 1432, from L. metricus "metrical," from Gk. metrikos, from metron "poetic meter."
caesura: 1556, from L., "metrical pause," lit. "a cutting," from pp. stem of cædere "to cut down" (see cement).
dactyl: late 14c., from Gk. dactylos "finger," of unknown origin; the metrical use (a long syllable followed by two short ones) is by analogy with the three joints of a finger.
iambic: 1575, from L. iambicus, from Gk. iambikos, from iambos "metrical foot of one unaccented followed by one accented syllable," from iaptein "to assail" (in words); the meter of invective and lampoon in classical Gk. from the time it was used for such by Archilochos, 7c. B.C.E.
pyrrhic (2): "dance in armor" (1597), also a type of metrical foot (1626), from L. pyrrhicha, from Gk. pyrrikhe orkhesis, the war-dance of ancient Greece, traditionally named for its inventor, Pyrrikhos. The name lit. means "reddish," from pyrros "flame-colored," from pyr "fire" (see pyre).
verse: c.1050, "line or section of a psalm or canticle," later "line of poetry" (c.1369), from Anglo-Fr. and O.Fr. vers, from L. versus "verse, line of writing," from PIE base *wer- "to turn, bend" (see versus). The metaphor is of plowing, of "turning" from one line to another (vertere = "to turn") as a plowman does. O.E. had fers, an early W.Gmc. borrowing directly from L. Meaning "metrical composition" is recorded from c.1300; sense of "part of a modern pop song" (as distinguished from the chorus) is attested from 1927. The English N.T. first divided fully into verses in the Geneva version (1551).
"Verse was invented as an aid to memory. Later it was preserved to increase pleasure by the spectacle of difficulty overcome. That it should still survive in dramatic art is a vestige of barbarism." [Stendhal, "De L'Amour," 1822]
nonce: abstracted from phrase for þe naness (c.1200) "for a special occasion, for a particular purpose," itself a misdivision of for þan anes "for the one," in reference to a particular occasion or purpose, the þan being from O.E. dative def. article þam. The phrase used from early 14c. as an empty filler in metrical composition. Hence, nonce-word "word coined for a special occasion," 1954.
thesis: late 14c., "unaccented syllable or note," from L. thesis "unaccented syllable in poetry," later "stressed part of a metrical foot," from Gk. thesis "a proposition," also "downbeat" (in music), originally "a setting down or placing," from root of tithenai "to place, put, set," from PIE base *dhe- "to put, to do" (see factitious). Sense in logic of "a proposition, statement to be proved" is first recorded 1570s; that of "dissertation written by a candidate for a university degree" is from 1650s.
chorale: 1841, "sacred choral song," from Ger. Choral "metrical hymn in Reformed church," shortened from Choralgesang "choral song," translating M.L. cantus choralis, from L. cantus (see chant) + choralis (see choral). The "-e" was added to indicate stress. Meaning "group of singers" is 1942.
foot: O.E. fot, from P.Gmc. *fot (cf. O.N. fotr, Du. voet, Ger. Fuß, Goth. fotus "foot"), from PIE *pod-/*ped- (cf. Avestan pad-; Skt. pat, acc. padam "foot;" Gk. pos, Attic pous, gen. podos; L. pes, gen. pedis "foot;" Lith. padas "sole," peda "footstep"). Plural form feet is an instance of i-mutation. Of a bed, grave, etc., first recorded 1300. The linear measurement of 12 inches is first recorded in O.E., from the length of a man's foot. To foot a bill is attested from 1848, from the process of tallying the expenses and writing the figure at the bottom ("foot") of the bill. Theatrical footlights is first attested 1836; footnote is from 1841. Colloquial exclamation my foot! expressing "contemptuous contradiction" is first attested 1923, probably a euphemism for my ass, in the same sense, which dates back to 1796. The metrical foot (O.E., translating L. pes, Gk. pous in the same sense) is commonly taken as a reference to keeping time by tapping the foot. To get off on the right foot is from 1909; to put one's best foot foremost first recorded 1849.
expletive: 1612, originally "a word or phrase serving to fill out a sentence or metrical line," from L.L. expletivus "serving to fill out," from L. explere "fill out," from ex- "out" + plere "to fill" (see plenary). Sense of "exclamation," often in the form of a cuss word, first recorded 1815 in Sir Walter Scott.
meter (1): "poetic measure," O.E. meter, from L. metrum, from Gk. metron "meter, measure," from PIE base *me- "measure" (see meter (2)). Possibly reborrowed early 14c. (after a 300-year gap in recorded use) from O.Fr. metre, with specific sense of "metrical scheme in verse," from L. metrum.
rondeau: 1525, from M.Fr. rondeau, from O.Fr. rondel (see rondel). Metrical form of 10 or 13 lines with only two rhymes.
rondel: 1390, from O.Fr. rondel "short poem," lit. "small circle," dim. of roont (fem. roonde) "circular" (see round). Metrical form of 14 lines with only two rhymes. So called because the initial couplet is repeated at the end.
song: O.E. sang "art of singing, a metrical composition adapted for singing," from P.Gmc. *sangwaz (cf. O.N. söngr, Norw. song, Swed. sång, O.S., Dan., O.Fris., O.H.G., Ger. sang, M.Du. sanc, Du. zang, Goth. saggws), related to sing (q.v.). Songbook is O.E. sangboc; song-bird is from 1774; songster is O.E. sangystre. Phrase for a song is from "All's Well" III.ii.9. With a song in (one's) heart "feeling of joy" is first attested 1930 in Lorenz Hart's lyric. Song and dance as a form of vaudeville act is attested from 1872; fig. sense of "rigmarole" is from 1895.
trimeter: "a verse of three metrical feet," 1567, from L. trimetrus, from Gk. trimetros "having three measures," from tri- "three" + metron "a measure" (see meter (2)).
trochee: 1589, from Fr. trochée, from L. trochaeus "a trochee," from Gk. trokhaios (pous), lit. "a running, spinning (foot)," from trekhein "to run." As a metrical foot, a long followed by a short syllable, or an accented followed by an unaccented one.
spondee: c.1390, "metrical foot consisting of two long syllables," from O.Fr. spondee, from L. spondeus, from Gk. spondeios (pous), the name of the meter originally used in chants accompanying libations, from sponde "solemn libation," related to spendein "make a drink offering," from PIE base *spend- "to make an offering, perform a rite," hence "to engage oneself by a ritual act" (cf. L. spondere "to engage oneself, promise," Hittite shipantahhi "I pour out a libation, I sacrifice").
ballade: early 14c., an earlier borrowing of ballad (q.v.) with a specific metrical sense. Technically, a poem consisting of one or more triplets of seven- (later eight-) lined stanzas, each ending with the same line as the refrain, usually with an envoy. Popularized 19c. as a type of musical composition by Frédéric Chopin. Ballade royal is recorded from late 15c.