1. a telephone service that allows callers to have conversations with other callers on the same line, typically for social or entertainment purposes
Usage: informal; chiefly British
2. an online service or platform where users can exchange text messages in real time with other users
Usage: informal; modern usage

Examples

• She called the chatline to talk with other people who shared her interests.
• The chatline was a popular way for teenagers to meet and chat before social media existed.
• He spent hours on the chatline discussing movies with strangers.
• The company launched a new chatline service for customer support.
• Many people used the chatline to find friends and have conversations late at night.