ungenerous, meanspirited -- (lacking in magnanimity; "it seems ungenerous to end this review of a splendid work of scholarship on a critical note"- Times Litt. Sup.; "a meanspirited man unwilling to forgive")
base, mean, meanspirited -- (having or showing an ignoble lack of honor or morality; "that liberal obedience without which your army would be a base rabble"- Edmund Burke; "taking a mean advantage"; "chok'd with ambition of the meaner sort"- Shakespeare; "something essentially vulgar and meanspirited in politics")