The Collaborative International Dictionary of English v.0.48:

Convalescence \Con`va*les"cence\, Convalescency
\Con`va*les"cen*cy\, n. [L. convalescentia: cf. F.
   convalescence.]
   The recovery of heath and strength after disease; the state
   of a body renewing its vigor after sickness or weakness; the
   time between the subsidence of a disease and complete
   restoration to health.
   [1913 Webster]