Synonyms of allowable

2 Syllables
legal, proper, venial
3 Syllables
bearable, relevant, conformant, warranted, syntactic, semantic, passable, open-door, permitted
4 Syllables
grammatical, acceptable, condonable, vindicable, remissible, admissible, sufferable, warrantable, justifiable, tolerable
5 Syllables
legitimate, applicatory