semimute

from The Century Dictionary.

• Noting a person who, owing to the loss of the sense of hearing, has lost also to a great extent the faculty of speech, or who, owing to congenital deafness, has never perfectly acquired that faculty.
• noun A person thus affected.

from the GNU version of the Collaborative International Dictionary of English.

• noun A semimute person.
• adjective Having the faculty of speech but imperfectly developed or partially lost.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Having the faculty of speech either imperfectly developed or partially lost.
• noun One who has the faculty of speech either imperfectly developed or partially lost.