Great in quantity, amount, degree, etc.
The definition of copious is something of which there is a large amount.
A profuse outpouring or quantity:
The determination or choice so made:
A plentiful or abundant supply; enough or more than enough
Consisting of some large, indefinite number (of persons or things); numerous
Find another word for not-a-little. In this page you can discover 10 synonyms, antonyms, idiomatic expressions, and related words for not-a-little, like: not a few, much, great, large, copious, profusion, abundance, lot, plenty and many.