ample - more than enough
e.g., You'll have ample opportunity to ask questions after the talk.
adequate - enough or satisfactory for a particular purpose
e.g., Have we got adequate food for twenty guests?
plentiful - if something is plentiful, there is a lot of it available
e.g., Strawberries are plentiful in the summer
sufficient - enough for a particular purpose
e.g., This recipe should be sufficient for five people
enough - is an *adverb, NOT an adjective
Oxford English Dictionary