WordNet sense 1 (enough to meet a purpose):

decent, enough

WordNet sense 2 (of a quantity that can fulfill a need or requirement but without being abundant):

sufficient

WordNet sense 3 (about average; acceptable):

passable, tolerable, fair to middling

WordNet sense 4 (giving satisfaction):

satisfactory

WordNet sense 5 (adequate for the purpose):

competent

WordNet sense 6 (having the requisite qualities for):

capable, equal to