Definition of bad penny in English:

bad penny

noun

figurative
  • A penny which is debased or counterfeit. In later use chiefly in the proverb a bad penny always returns (also turns up), and (now especially) in similative or figurative use in allusion to this, with reference to the predictable, and often unwanted, return of a disreputable or prodigal person after some absence, or (more generally) to the continual recurrence of someone or something.

Origin

Late Middle English; earliest use found in William Langland (c1325–c1390), poet. From bad + penny.

Pronunciation

bad penny

/ˌbad ˈpɛni/