plural monsters
1
: a strange or horrible imaginary creature
mythical monsters
a sea monster
a monster movie [=a movie about monsters]
2
informal
: something that is extremely or unusually large
That car is a monster.
It's a monster of a house. [=a very large house]
3
: a powerful person or thing that cannot be controlled and that causes many problems
Inflation has become an economic monster.
4
a
: an extremely cruel or evil person
His father was a monster who punished his children for no reason.
You don't want to work for that monster.
b
: a person (such as a child) who behaves very badly
My nephew is a little monster.
always used before a noun
informal
: very popular and successful
The movie turned out to be a monster hit.
a monster band
Cite this Entry
“Monster.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/monster. Accessed 21 Jun. 2026.
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