内通者
Meanings
1
mole; whistle-blower; informant; betrayer
Refers to someone who secretly passes inside information to an opposing party, often in espionage, organizations, or criminal contexts.
The police discovered that there was a mole inside the organization.
He is a whistle-blower who exposed the company's wrongdoing.
2
Rare, old-fashioned use for someone who commits adultery. Modern Japanese typically uses 不倫相手 or 浮気相手.
In old novels, the word 内通者 can refer to an adulterous partner.