Examination of the mouth (4)
I believe the answer is:
oral
I believe this is a double definition.
'examination' is the first definition.
(oral is a kind of examination)
'of the mouth' is the second definition.
(I've seen this before)
(Other definitions for oral that I've seen before include "Verbal" , "By word of mouth (4)" , "from the trap" , "Like some tradition" , "language exam" .)