1.
demon; monster; evil spirit
A supernatural creature that brings harm or misfortune. Used in folklore, fantasy fiction, and games.
森に魔物が住んでいる。
A monster lives in the forest.
勇者が魔物を倒した。
The hero defeated the monster.
伝説によると、この山には恐ろしい魔物が封じられているという。
According to legend, a terrifying demon is sealed in this mountain.
2.
an unpredictable force; something bewitching
Used figuratively for an unseen force that disrupts outcomes, especially in sports or competitions. Also for something that has a dangerous allure.
勝負には魔物が潜む。
Competitions have an unpredictable element lurking within them.
本番には魔物がいると言われている。
They say there's a jinx lurking in live performances.
オリンピックには魔物が棲んでいるとよく言われるが、今回もまさにそうだった。
People often say there's a jinx at the Olympics, and this time was no exception.
USAGE NOTES:
魔物 appears frequently in fantasy games, anime, and folklore. In sense 2, it is a common sports/competition metaphor meaning that unexpected things happen under pressure.
SIMILAR WORDS:
- 化け物 — a shape-shifting monster from Japanese folklore
- 怪物 — a monster or prodigy (can refer to people with extraordinary ability)
- 悪魔 — devil, specifically evil
- 妖怪 — supernatural creatures from Japanese tradition
COMMON COLLOCATIONS:
- 魔物を倒す (defeat a monster)
- 魔物が潜む (a jinx/unpredictable force lurks)
- 魔物が棲む (a jinx inhabits)
The figurative sense 2 is a set expression in sports commentary: 勝負には魔物が潜む means "anything can happen in a competition."