Human (6)
(Other definitions for person that I've seen before include "Individual human being" , "character" , "present appearing in this" , "Type" , "he's the third" .)
'human' is the definition.
(synonyms)
This is all the clue.
(Other definitions for mortal that I've seen before include "liable to die" , "Certain to die" , "Fatal" , "Human - transitory" , "Causing death" .)