To act as a tattletale; to tell on; to give away, reveal, or expose.
telltale; giveaway
One who tattles (reports others' wrongdoings), often a child seeking attention.
One who gossips, often for the sake of attention.
To act the traitor toward; to betray; to deceive.
One who betrays any confidence or trust.
Someone who violates an allegiance and betrays their country; someone guilty of treason; one who, in breach of trust, delivers their country to an enemy, or yields up any fort or place entrusted to their defense, or surrenders an army or body of troops to the enemy, unless when vanquished.
Someone who takes arms and levies war against their country; or one who aids an enemy in conquering their country.
Traitorous.