The Collaborative International Dictionary of English v.0.48:

Perceptible \Per*cep"ti*ble\ (p[~e]r*s[e^]p"t[i^]*b'l), a. [L.
   perceptibilis: cf. F. perceptible. See Perceive.]
   Capable of being perceived; cognizable; discernible;
   perceivable; large enough to be perceived; not so small as to
   be incapable of perception.
   [1913 Webster]

         With a perceptible blast of the air.     --Bacon.
   [1913 Webster] -- Per*cep"ti*ble*ness, n. --
   Per*cep"ti*bly, adv.
   [1913 Webster]