collection [n]:

group, accumulation, acquiring, agglomeration, amassing, assemblage, assembling, batch, bringing together, clump, cluster, collation, compilation, cumulation, gathering, hoard, lot, mass, number, obtaining, pile, quantity, securing, set, stock, stockpile, store.



horizon [n]:

skyline, extent, border, boundary, compass, field of vision, limit, perspective, purview, range, reach, realm, scope, stretch, vista

line at which earth & sky appear to meet; apparent, sensible, visible

limit of mental perception, experience, interest, etc.