From WordNet (r) 2.0 (August 2003) [wn]:
stacks
n 1: a large number or amount; "made lots of new friends"; "she
amassed a mountain of newspapers" [syn: tons,
dozens, heaps, lots, mountain, piles,
scores, loads, rafts, slews, wads, oodles,
gobs, scads, lashings]
2: storage space consisting of an extensive arrangement of
bookshelves in a library where most of the books are
stored [syn: set of bookshelves]