enthusiast

In modern usage, "enthusiasm" refers to intense enjoyment, interest, or approval expressed by a person. The term is allegedly related to playfulness, inventiveness, optimism, zest, verve, and high energy.
People can often characterise the modern version of enthusiasm as "infectious" or "contagious",
and sometimes even more metaphorically as a virus in its own right.
The word once applied, in accordance with its etymology,
to persons possessed by a god, or to people who exhibited intense piety.

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