overheard
v.v. to hear what other people are saying without them knowing you are listening. This usually happens by accident because you are nearby.
v. to hear speech or conversation without the speaker's intention or knowledge. The past tense and past participle of 'overhear'.
I overheard them talking about the surprise party.
While waiting for my coffee, I accidentally overheard two managers discussing the upcoming office relocation.
In many classic novels, the plot hinges on a character who has overheard a private confession, leading to a series of misunderstandings that drive the narrative toward its climax.
Transitive verb; typically takes a direct object or a clause starting with 'that'.
I overheard to their conversationI overheard their conversationOverhear is a transitive verb and does not take the preposition 'to' before the object.