WordNet sense 1 (lacking power of speech):

mute

WordNet sense 2 (not capable of or especially not involving speech or spoken lines):

nonspeaking, walk-on

WordNet sense 3 (expressed without speech; especially because words would be inappropriate or inadequate):

unspoken, wordless

WordNet sense 4 (without or deprived of the use of speech or words):

inarticulate, unarticulate