The Collaborative International Dictionary of English v.0.48:

Insentient \In*sen"ti*ent\, a.
   Not sentient; not having perception, or the power of
   perception; devoid of feeling, consciousness and animation;
   inanimate; as, insentient stone. Opposite of sentient.
   [WordNet sense 1+3]

   Syn: inanimate, insensate.
        [1913 Webster + WordNet 1.5]

              The . . . attributes of an insentient, inert
              substance.                          --Reid.
        [1913 Webster]

              But there can be nothing like to this sensation in
              the rose, because it is insentient. --Sir W.
                                                  Hamilton.
        [1913 Webster]

   2. incapable of sensation.

   Syn: insensate, insensible.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

insentient
    adj 1: devoid of feeling and consciousness and animation;
           "insentient (or insensate) stone" [syn: insentient,
           insensate] [ant: animate, sentient]