noun
tough guy; fearless fighter; wild one
Refers to a strong, brave, or reckless person, often with a rough or wild image. Can be used admiringly or critically.
彼は戦場で猛者として知られていた。
He was known as a fearless fighter on the battlefield.
あの新入社員はなかなかの猛者だ。
That new employee is quite a tough guy.
強者 also means a strong or brave person, but often emphasizes military prowess or a veteran. 猛者 focuses more on a wild, fearless, or reckless character.
豪傑 is a more literary term for a hero or great man, often with a larger-than-life quality, while 猛者 is more colloquial and can be used for everyday tough guys.
The kanji 猛 means 'fierce' or 'wild', and 者 means 'person'. The reading もさ is a standard on'yomi combination. The obsolete reading もうざ reflects an older pronunciation.