What does antimeriden and primemeriden mean?

Antimeridian refers to the line of longitude that is 180 degrees opposite the Prime Meridian, essentially marking the halfway point around the globe. It is significant in navigation and timekeeping, as it serves as a dividing line between one calendar day and the next. The Prime Meridian, located at 0 degrees longitude, is the reference point from which all other longitudes are measured. Together, they help define time zones and geographical orientation.