Stands for "Fear Of Missing A Shot". Like Fomo (fear of missing out).
Fomas applies to photographers, videographers, and timelapse photographers. Someone with FOMAS is constantly seeing things how they imagine their camera to see things, and looking for photos, videos or timelapses everywhere. They must always have their camera out, and normally switched on.
Person 1: "Duuuude, put your camera away and come and enjoy the party"
Person 2: "Sorry bro, cant because of FOMAS"