Forenoon is the part of the day between sunrise and noon, essentially another way of saying “morning.” If someone schedules a meeting for the forenoon, they mean sometime before 12:00 p.m.

The word sounds old-fashioned because it is: people used to say forenoon more commonly, especially in formal contexts or when they wanted to be precise about timing. You might encounter it in older books or historical documents. Sailors and people in the military still sometimes use forenoon to describe the morning watch or work period.

Its opposite, afternoon, is much more common today. While you can say “I'll see you in the forenoon” and people will understand you mean the morning, most people would simply say “I'll see you in the morning” or “I'll see you before noon.”