I know one person who may revise the use of this word to define himself after perusing its ultimate meaning... |-)
1. Great excitement for or interest in a subject or cause.
2. A source or cause of great excitement or interest.
Ecstasy arising from supposed possession by a god.
Late Latin enthsiasmus, from Greek enthousiasmos, from enthousiazein, to be inspired by a god, from entheos, possessed : en-, in ; see en- 2 + theos, god; see dhs- in Indo-European roots
"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 enthusiasmone positive and one negativeboth 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.