Synonyms of the word

speechless

• adj. not speaking; not knowing what to say; silent, especially due to surprise, amazement, etc.

dumb

• adj. (dated) Unable to speak; lacking power of speech (kept in "deaf, dumb, and blind").
• adj. (dated) Silent; unaccompanied by words.
• adj. (informal, pejorative, especially of a person) extremely stupid.
• adj. (figuratively) Pointless, foolish, lacking intellectual content or value.
• adj. Lacking brightness or clearness, as a colour.
• v. (dated) To silence.
• v. (transitive) To make stupid.
• v. (transitive) To represent as stupid.
• v. (transitive) To reduce the intellectual demands of.

inarticulate

• adj. (of speech) not articulated in normal words.
• adj. speechless.
• adj. unable to speak with any clarity.
• adj. (biology) not having joints or other articulations.
• n. (zoology) An animal belonging to the subphylum Inarticulata.