1610s, "pertaining to play or sport" (a sense now obsolete), from Latin ludicrus "sportive" (source of Old French ludicre), from ludicrum "amusement, game, toy, source of amusement, joke," from ludere "to play."
This verb, along with Latin ludus "a game, play," is from the PIE root *leid- or *loid- "to play," perhaps literally "to let go frequently" [de Vaan], which is the source also of Middle Irish laidid "impels;" Greek lindesthai "to contend," lizei "plays;" Albanian lind "gives birth," lindet "is born;" Old Lithuanian leidmi "I let," Lithuanian leisti "to let," laidyti "to throw," Latvian laist "let, publish, set in motion."
Sense of "ridiculous, apt to evoke ridicule or jest" is attested from 1782. Related: Ludicrously; ludicrousness.
"secret agreement for fraudulent or harmful purposes," late 14c., from Old French collusion and directly from Latin collusionem (nominative collusio) "act of colluding," from colludere, from assimilated form of com "with, together" (see com-) + ludere "to play" (see ludicrous). "The notion of fraud or underhandedness is essential to collusion" [Fowler].
"introductory performance; a preliminary to an action event or work," 1560s, from French prélude "notes sung or played to test the voice or instrument" (1530s), from Medieval Latin preludium "prelude, preliminary," from Latin praeludere "to play beforehand for practice, preface," from prae- "before" (see pre-) + ludere "to play" (see ludicrous). Purely musical sense of "movement or piece forming the introduction to a musical work" is attested in English by 1650s. Related: Preludial; prelusive; prelusory; preludious; prelusion.
1530s, "to mock" (transitive, now obsolete), from French alluder or directly from Latin alludere "to play, make fun of, joke, jest," also of waves lapping the shore, from assimilated form of ad "to" (see ad-) + ludere "to play" (see ludicrous). Meaning "make an indirect reference, point in passing" is from 1530s. Related: Alluded; alluding.