Lyrics are words that make up a song, usually consisting of verses and choruses. The writer of lyrics is a lyricist. The words to an extended musical composition such as an opera are, however, usually known as a "libretto" and their writer, as a "librettist". The meaning of lyrics can either be explicit or implicit. Some lyrics are abstract, almost unintelligible, and, in such cases, their explication emphasizes form, articulation, meter, and symmetry of expression. Rappers can also create lyrics (often with a variation of rhyming words) that are meant to be spoken rhythmically rather than sung. Etymology The word lyric derives via Latin from the Greek (), the adjectival form of lyre. It first appeared in English in the mid-16th century in reference to the Earl of Surrey's translations of Petrarch and to his own sonnets. Greek lyric poetry had been defined by the manner in which it was sung accompanied by the lyre or cithara, as opposed to the chanted formal epics or the more passionate elegies accompanied by the flute. The personal nature of many of the verses of the Nine Lyric Poets led to the present sense of "lyric poetry" but the original Greek sense of "lyric poetry""poetry accompanied by the lyre" i.e. "words set to music"eventually led to its use as "lyrics", first attested in Stainer and Barrett's 1876 Dictionary of Musical Terms. Stainer and Barrett used the word as a singular substantive: "Lyric, poetry or blank verse intended to be set to music and sung". By the 1930s, the present use of the plurale tantum "lyrics" had begun; it has been standard since the 1950s for many writers. The singular form "lyric" is still used to mean the complete words to a song by authorities such as Alec Wilder, Robert Gottlieb, and Stephen Sondheim. However, the singular form is also commonly used to refer to a specific line (or phrase) within a song's lyrics. Poems The differences between poem and song may become less meaningful where verse is set to music, to the point that any distinction becomes untenable. This is perhaps recognised in the way popular songs have lyrics. However, the verse may pre-date its tune (in the way that "Rule Britannia" was set to music, and "And did those feet in ancient time" has become the hymn "Jerusalem"), or the tune may be lost over time but the words survive, matched by