The Collaborative International Dictionary of English v.0.48:

Inmate \In"mate`\ ([i^]n"m[=a]t`), n. [In + mate an associate.]
   One who lives in the same house or apartment with another; a
   fellow lodger; esp., one of the occupants of an asylum,
   hospital, or prison; by extension, one who occupies or lodges
   in any place or dwelling.
   [1913 Webster]

         So spake the enemy of mankind, inclos'd
         In serpent, inmate bad.                  --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Inmate \In"mate`\, a.
   Admitted as a dweller; resident; internal. [R.] "Inmate
   guests." --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inmate
    n 1: one of several resident of a dwelling (especially someone
         confined to a prison or hospital)
    2: a patient who is residing in the hospital where he is being
       treated [syn: inpatient, inmate] [ant: outpatient]
    3: a person serving a sentence in a jail or prison [syn:
       convict, con, inmate, yard bird, yardbird]