I think 'glomus' is Latin for 'a ball'
Excellent point, Clive. 'Aggregate' and 'congregate' are more appropriate to flat work.
When I've taught a studio class in collage, however, I always approached the word ('collage') as a principle of organization. That approach allowed students of various disciplines, like sculpture, film, painting, even some music majors, to feel at home in the same 'studio'.