Online Etymology Dictionary

myrrh (n.): Old English myrre, from Latin myrrha (also source 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."
myrtle (n.): 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).
myself (pron.): c. 1500, alteration of meself, from Old English phrase (ic) me self, where me is "a kind of ethical dative" [OED], altered in Middle Ages from meself on analogy of herself, with her- felt as genitive; though analogous hisself remains bad form.
mysophobia (n.): "dread of dirt or defilement," 1879, from Greek mysos "uncleanliness," from PIE *meus- "damp" (see moss) + -phobia.
MySpace: social networking Web site, founded in late 2003.
mystagogue (n.): "person who initiates into mysteries," 1550s, from Latin mystagogus "a guide to the mysteries," from Greek mystagogos, from mystes "one initiated into the mysteries" (see mystery (n.1)) + agogos "leading, a leader" (see act (n.)). Related: Mystagogic; mystagogical; mystagogy; mystagoguery.
mysterious (adj.): 1610s, "full of mystery," from Latin mysterium (see mystery (n.1)) + -ous. Related: Mysteriously; mysteriousness. Earlier in same sense was mysterial (early 15c.), from Late Latin mysterialis.
God moves in a mysterious way,
His wonders to perform;
He plants his footsteps in the sea,
And rides upon the storm

[Cowper, from the "Olney Hymns," 1779]
mystery (n.1): early 14c., in a theological sense, "religious truth via divine revelation, hidden spiritual significance, mystical truth," from Anglo-French *misterie, Old French mistere "secret, mystery, hidden meaning" (Modern French mystère), from Latin mysterium "secret rite, secret worship; a secret thing," from Greek mysterion (usually in plural mysteria) "secret rite or doctrine," from mystes "one who has been initiated," from myein "to close, shut" (see mute (adj.)); perhaps referring to the lips (in secrecy) or to the eyes (only initiates were allowed to see the sacred rites).

The Greek word was used in Septuagint for "secret counsel of God," translated in Vulgate as sacramentum. Non-theological use in English, "a hidden or secret thing," is from late 14c. In reference to the ancient rites of Greece, Egypt, etc. it is attested from 1640s. Meaning "detective story" first recorded in English 1908.
mystery (n.2): "handicraft, trade, art" (archaic), late 14c., from Medieval Latin misterium, alteration of Latin ministerium "service, occupation, office, ministry" (see ministry), influenced in form by Medieval Latin mysterium (see mystery (n.1)) and in sense by maistrie "mastery." Now only in mystery play, in reference to the medieval performances, which often were staged by members of craft guilds. The two senses of mystery formed a common pun in (secular) Tudor theater.
mystic (adj.): late 14c., "spiritually allegorical, pertaining to mysteries of faith," from Old French mistique "mysterious, full of mystery" (14c.), or directly from Latin mysticus "mystical, mystic, of secret rites" (source also of Italian mistico, Spanish mistico), from Greek mystikos "secret, mystic, connected with the mysteries," from mystes "one who has been initiated" (see mystery (n.1)). Meaning "pertaining to occult practices or ancient religions" first recorded 1610s.
mystic (n.): "exponent of mystical theology," 1670s, from mystic (adj.). In Middle English, the noun meant "symbolic meaning, interpretation" (early 14c.).
Mystic: place name in Connecticut, U.S., deformed from Algonquian missituk "great tidal river," from missi "large" + -tuk "tidal river."
mystical (adj.): late 15c., "enigmatic, obscure, symbolic," from mystic + -al (1). Related: Mystically. Meaning "having spiritual significance" is from 1520s.
mysticism (n.): 1736, from mystic (adj.) + -ism.
mystification (n.): 1815, from French mystification, noun of action from mystifier (see mystify).
mystified (adj.): "bewildered, puzzled," 1863, past participle adjective from mystify.
mystify (v.): 1814, from French mystifier (1772), a verb formed irregularly from mystique "a mystic" (see mystic (adj.)) + -fier (see -fy). Related: Mystified; mystifying.
mystique (n.): 1891, "atmosphere of mystery," from French mystique "a mystic; mystical," from Latin mysticus (see mystic (adj.)).
myth (n.): 1830, from French Mythe (1818) and directly from Modern Latin mythus, from Greek mythos "speech, thought, story, myth, anything delivered by word of mouth," of unknown origin.
Myths are "stories about divine beings, generally arranged in a coherent system; they are revered as true and sacred; they are endorsed by rulers and priests; and closely linked to religion. Once this link is broken, and the actors in the story are not regarded as gods but as human heroes, giants or fairies, it is no longer a myth but a folktale. Where the central actor is divine but the story is trivial ... the result is religious legend, not myth." [J. Simpson & S. Roud, "Dictionary of English Folklore," Oxford, 2000, p.254]
General sense of "untrue story, rumor" is from 1840.
mythic (adj.): 1660s, from Late Latin mythicus "legendary," from Greek mythikos, from mythos (see myth).
mythical (adj.): 1670s; see mythic + -al (1).
mythological (adj.): 1610s, from Late Latin mythologicus, from Greek mythologikos "versed in legendary lore," from mythologia (see mythology). Related: Mythologically.
mythology (n.): early 15c., "exposition of myths," from Middle French mythologie and directly from Late Latin mythologia, from Greek mythologia "legendary lore, a telling of mythic legends; a legend, story, tale," from mythos "myth" (of unknown origin) + -logy "study." Meaning "a body of myths" first recorded 1781.
mythopoeic (adj.): "pertaining to the creation of myths," 1846, from Greek mytho-, comb. form of mythos (see myth) + poiein "to make, create" (see poet).
myxo-: before vowels myx-, word-forming element meaning "slime, mucus," from comb. form of Greek myxa "mucus; lamp wick" (see mucus).