Homonym: 10-4 (Acknowledgment)
"10-4" is a code used in two-way radio communication, particularly among truck drivers and emergency services. It is part of the ten-codes, which were developed to convey information quickly and clearly. When someone says "10-4," it means "message received" or "acknowledged."
The use of "10-4" has become popular in everyday language, often used to indicate agreement or understanding. While it originated in radio communication, it is now commonly recognized in various contexts, including movies and television shows, where characters use it to confirm instructions or information.