* In a relationship: A person who is unfaithful in a romantic relationship is cheating on their partner. This could involve having an affair, engaging in sexual activity with someone else, or simply breaking promises or commitments.
* In a friendship: An unfaithful friend might betray your confidence, spread rumors about you, or abandon you in times of need.
* In a religious context: An unfaithful person might abandon their faith or beliefs.
* In general: You can also use "unfaithful" to describe someone who is not truthful or reliable, such as an unfaithful employee who steals from their employer.
The specific meaning of "unfaithful" will depend on the context in which it is used. However, it always implies a violation of trust or loyalty.