The term 'flaps one's gums' is an idiom that means to talk excessively and without purpose. The crossword solutions for this term are 'NATTERS' (7 letters), 'GABS' (4 letters), 'YAPS' (4 letters), and 'YAKS' (4 letters). All of these words have similar meanings, with 'NATTER' being the most formal and 'YAK' being the least formal. All of these words refer to talking too much, often in a way that is not productive or meaningful.