Webster's English Dictionary

Enter the word to look up:

id

1. id \'id\ n [NL, fr. L, it] : the undifferentiated source of the 
   organism's energy from which both ego  and libido are derived
2. id n [-id, fr. F -ide, fr. L -id-, -is, fem. patronymic suff]ix : an 
   allergic skin rash that is secondary to a primary infection elsewhere  in 
   or on the body