In sign language, mouthing is the production of visual syllables with the mouth while signing. That is, signers sometimes say or mouth a word in a spoken language at the same time as producing the sign for it. Mouthing is one of the many ways in which the face and mouth is used while signing. Although not present in all sign languages, and not in all signers, where it does occur it may be an essential element of a sign, distinguishing signs which would otherwise be homophones; in other cases a sign may seem to be flat and incomplete without mouthing even if it is unambiguous. Other signs use a combination of mouth movements and hand movements to indicate the sign; for example, the ASL sign for not-yet includes a mouth gesture where the mouth is slightly open.