c. 1600, from French enthousiasme (16c.) and directly from Late Latin enthusiasmus, from Greek enthousiasmos "divine inspiration, enthusiasm (produced by certain kinds of music, etc.)," from enthousiazein "be inspired or possessed by a god, be rapt, be in ecstasy," from entheos "divinely inspired, possessed by a god," from en "in" (see en- (2)) + theos "god" (from PIE root *dhes-, forming words for religious concepts). It acquired a derogatory sense of "excessive religious emotion through the conceit of special revelation from God" (1650s) under the Puritans; generalized meaning "fervor, zeal" (the main modern sense) is first recorded 1716.
1827, American English, back-formation from enthusiasm. Originally often humorous or with affected ignorance. Related: enthused; enthusing.
1560s, pejorative, "one who believes himself possessed of divine revelations or special communication from God," from Greek enthousiastes "a person inspired," from enthousiazein (see enthusiasm). General sense (not always entirely pejorative) is from mid-18c.
c. 1600, "pertaining to possession by a deity," from Greek enthousiastikos "inspired," from enthousiazein "be possessed or inspired by a god" (see enthusiasm). Meaning "pertaining to irrational delusion in religion" is from 1690s. The main modern sense, in reference to feelings or persons, "intensely eager, rapturous," is from 1786. Related: Enthusiastically.
*dhēs-, Proto-Indo-European root forming words for religious concepts. Possibly an extension of PIE root *dhe- "to set, put."
It forms all or part of: apotheosis; atheism; atheous; Dorothy; enthusiasm; fair (n.) "a stated market in a town or city;" fanatic; ferial; feast; fedora; -fest; festal; festival; festive; festoon; Festus; fete; fiesta; henotheism; monotheism; pantheism; pantheon; polytheism; profane; profanity; Thea; -theism; theist; theo-; theocracy; theodicy; Theodore; Theodosia; theogony; theology; theophany; Theophilus; theosophy; theurgy; tiffany; Timothy.
It is the hypothetical source of/evidence for its existence is provided by: Greek theos "god;" Latin feriae "holidays," festus "festive," fanum "temple."
1690s, "special talent in writing, enthusiasm in what pertains to art and literature," from French verve "enthusiasm" (especially pertaining to the arts), in Old French "caprice, odd humor, proverb, saying; messenger's report" (12c.), probably from Gallo-Roman *verva, from Latin verba "(whimsical) words," plural of verbum "word" (see verb). Meaning "mental vigor" is first recorded 1803.
"to burst into flame, burn brightly or vigorously," c. 1200, from blaze (n.1). To blaze away "fire (guns or cannon) continuously" is by 1776, hence "work with vigor and enthusiasm." Related: Blazed; blazing.