enthusiasm

noun

1. Great excitement for or interest in a subject or cause.
2. A source or cause of great excitement or interest.
3. Archaic
   a. Ecstasy arising from supposed possession by a god.
   b. Religious fanaticism.

Origin:

Origin: Late Latin enthūsiasmus

Origin: , from Greek enthousiasmos

Origin: , from enthousiazein, to be inspired by a god

Origin: , from entheos, possessed

Origin: : en-, in; see en-²

Origin: + theos, god; see dhēs- in Indo-European roots

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Word History: “Nothing great was ever achieved without enthusiasm,” said the very quotable Ralph Waldo Emerson, who also said, “Everywhere the history of religion betrays a tendency to enthusiasm.” These two uses of the word enthusiasm—one positive and one negative—both derive from its source in Greek. Enthusiasm first appeared in English in 1603 with the meaning “possession by a god.” The source of the word is the Greek enthousiasmos, which ultimately comes from the adjective entheos, “having the god within,” formed from en, “in, within,” and theos, “god.” Over time the meaning of enthusiasm became extended to “rapturous inspiration like that caused by a god” to “an overly confident or delusory belief that one is inspired by God,” to “ill-regulated religious fervor, religious extremism,” and eventually to the familiar sense “craze, excitement, strong liking for something.” Now one can have an enthusiasm for almost anything, from water skiing to fast food, without religion entering into it at all