inarticulate (adj.)

• ambiguous
• aphasic
• aphonic
• bashful
• blurred
• breathless
• choked
• confused
• conscious
• coy
• demure
• digressive
• discursive
• disjointed
• dumb
• dumbfounded
• dumbstricken
• dumbstruck
• faltering
• garbled
• guttural
• halting
• harsh
• hawking
• hesitating
• hoarse
• illogical
• impenetrable
• implicit
• incognizable
• incoherent
• incomprehensible
• indistinct
• inscrutable
• irrational
• jumbled
• mixed-up
• mousy
• muddled
• muffled
• mum
• mute
• muzzy
• nasal
• numinous
• quavering
• rambling
• scrambled
• self-conscious
• shaking
• shaky
• shamefaced
• shy
• silent
• skittish
• snuffling
• speechless
• stifled
• strangled
• thick
• throaty
• timid
• timorous
• tongue-tied
• tongueless
• tremulous
• unclear
• unconnected
• undeclared
• unexpressed
• unfathomable
• unintelligible
• unknowable
• unsaid
• unspoken
• unuttered
• velar
• voiceless
• wild
• wordless