1
adj abundant, a lot of, ample, considerable, copious, great, plenteous, plenty of, sizeable, substantial
2
adv a great deal, a lot, considerably, decidedly, exceedingly, frequently, greatly, indeed, often, regularly
3
n a good deal, a great deal, a lot, an appreciable amount, heaps (informal) loads (informal) lots (informal) plenty
Antonyms
, adj inadequate, insufficient, little, scant
adv barely, hardly, infrequently, irregularly, not a lot, not much, occasionally, only just, rarely, scarcely, seldom, slightly
n hardly anything, little, next to nothing, not a lot, not much, practically nothing, very little