"numberless, multitudinous," c. 1800, from myriad (n.).

1550s, "the number of 10,000," also "an indefinitely great number," from Middle French myriade and directly from Late Latin myrias (genitive myriadis) "ten thousand," from Greek myrias (genitive myriados) "a number of ten thousand; countless numbers," from myrios (plural myrioi) "innumerable, countless, infinite; boundless," as a definite number, "ten thousand" ("the greatest number in Greek expressed by one word," Liddell & Scott say), of unknown origin; perhaps from PIE *meue- "abundant" (source also of Hittite muri- "cluster of grapes," Latin muto "penis," Middle Irish moth "penis"). Beekes offers "no etymology." The numerically specific use is usually in translations from Greek or Latin.

one of a warlike people of ancient Thessaly, legendarily ruled by Achilles and accompanying him to Troy, c. 1400, from Latin Myrmidones (plural), from Greek Myrmidones, Thessalian tribe led by Achilles to the Trojan War, fabled to have been ants changed into men, and often derived from Greek myrmex "ant" (from PIE *morwi- (see Formica (2)), but Watkins does not connect them and Klein's sources suggest a connection to Greek mormos "dread, terror." Transferred sense of "faithful unquestioning follower," often with a suggestion of unscrupulousness, is from c. 1600.

"gummy, resinous exudation of certain plants of Arabia and Ethiopia," used for incense, perfumery, etc., Middle English mirre, from Old French mirre (11c.) and also from Old English myrre, both the Old English and Old French words from Latin myrrha (source also of Dutch mirre, German Myrrhe, French myrrhe, Italian, Spanish mirra), from Greek myrrha, from a Semitic source (compare Akkadian murru, Hebrew mor, Arabic murr "myrrh"), from a root meaning "was bitter." The classical spelling restoration is from 16c.

evergreen bush with fragrant white flowers, c. 1400, from Old French mirtile, from Medieval Latin myrtillus, diminutive of Latin myrtus "myrtle tree," from Greek myrtos "the myrtle, a sprig of myrtle," from same Semitic source as Greek myrrha (see myrrh). In ancient times it was sacred to Venus. The modern word is also applied to similar plants, some unrelated. Earlier Middle English forms were myrt, from Latin, and myrtine, from Medieval Latin myrtinus.

emphatic or reflexive form of I or me, c. 1500, mi-self, alteration of meself (c. 1200), from Old English phrase (ic) me self, where me is "a kind of ethical dative" [OED]. See my + self. The alteration from meself is by analogy of herself, where her- was felt as genitive (though analogous hisself remains bad form).

"morbid fear of contamination, dread of dirt or defilement," 1879, from Greek mysos "uncleanliness," which is of uncertain origin; perhaps from PIE *meus- "damp" (see moss) + -phobia.

social networking Web site, founded in late 2003 and dominant from 2005 to 2009.

"person who initiates into mysteries," 1550s, from Latin mystagogus "a guide to the mysteries," from Greek mystagōgos, from mystēs "one initiated into the mysteries" (see mystery (n.1)) + agōgos "leading, a leader," from agein "to lead" (from PIE root *ag- "to drive, draw out or forth, move"). Related: Mystagogic; mystagogical.

"interpretation of mysteries; the practice of a mystagogue," 1570s, from French mystagogie, from Latin mystagogia, from Greek mystagōgia "initiation into the mysteries," from mystagōgos "one who initiates into the mysteries" (see mystagogue). Related: Mystagoguery (1927).