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fiend

1 ENTRIES FOUND:
fiend /ˈfiːnd/ noun
plural fiends
fiend
/ˈfiːnd/
noun
plural fiends
Britannica Dictionary definition of FIEND
[count]
: an evil spirit : a demon or devil
: a very evil or cruel person
informal
: a person who is very enthusiastic about something : fanatic
: a person who is addicted to a drug or to a kind of behavior

like a fiend

chiefly US, informal
used to say that someone does a lot of something