The Collaborative International Dictionary of English v.0.48:

Convalescent \Con`va*les"cent\, a. [L. convalescens, -entis, p.
   pr.: cf. F. convalescent.]
   1. Recovering from sickness or debility; partially restored
      to health or strength.
      [1913 Webster]

   2. Of or pertaining to convalescence.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Convalescent \Con`va*les"cent\, n.
   One recovering from sickness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

convalescent
    adj 1: returning to health after illness or debility;
           "convalescent children are difficult to keep in bed"
           [syn: convalescent, recovering]
    n 1: a person who is recovering from illness