excusable

[L. excusabilis: cf. F. excusable. See Excuse.]
That may be excused, forgiven, justified, or acquitted of blame; pardonable; as, the man is excusable; an excusable action. -- Ex·cus·a·ble·ness, n. -- Ex·cus·a·bly, adv.

The excusableness of my dissatisfaction.

adjective

1. Admitting of forgiveness or pardon: forgivable, pardonable, venial. See forgiveness/vindictiveness.
2. Capable of being justified: defensible, justifiable, tenable. See forgiveness/vindictiveness, right/wrong.

Definition: allowable
Antonyms: blamable, inexcusable, unallowable, unforgivable, unjustifiable

The adjective has 2 meanings:

Meaning #1: capable of being overlooked
  Antonym: inexcusable (meaning #1)

Meaning #2: easily excused or forgiven
  Synonyms: forgivable, venial