Source : Webster's Revised Unabridged Dictionary (1913)

Latent \La"tent\, a. [L. latens, -entis, p. pr. of latere to lie
   hid or concealed; cf. Gr. ?, E. lethargy: cf. F. latent.]
   Not visible or apparent; hidden; springs of action.

         The evils latent in the most promising contrivances are
         provided for as they arise.              --Burke.

   {Latent buds} (bot.), buds which remain undeveloped or
      dormant for a long time, but may at length grow.

   {Latent heat} (Physics), that quantity of heat which
      disappears or becomes concealed in a body while producing
      some change in it other than rise of temperature, as
      fusion, evaporation, or expansion, the quantity being
      constant for each particular body and for each species of
      change.

   {Latent period}.
   (a) (Med.) The regular time in which a disease is supposed to
       be existing without manifesting itself.
   (b) (Physiol.) One of the phases in a simple muscular
       contraction, in which invisible preparatory changes are
       taking place in the nerve and muscle.
   (c) (Biol.) One of those periods or resting stages in the
       development of the ovum, in which development is arrested
       prior to renewed activity.

Source : WordNet®

latent period
     n 1: the time that elapses between a stimulus and the response to
          it [syn: {reaction time}, {response time}, {latency}]
     2: the time that elapses before the presence of a disease is
        manifested by symptoms