The Collaborative International Dictionary of English v.0.48:

Prodigal \Prod"i*gal\, a. [L. prodigus, from prodigere to drive
   forth, to squander away; pro forward, forth + agere to drive;
   cf. F. prodigue. See Agent. ]
   Given to extravagant expenditure; expending money or other
   things without necessity; recklessly or viciously profuse;
   lavish; wasteful; not frugal or economical; as, a prodigal
   man; the prodigal son; prodigal giving; prodigal expenses.
   [1913 Webster]

         In fighting fields [patriots] were prodigal of blood.
                                                  --Dryden.
   [1913 Webster]

   Syn: Profuse; lavish; extravagant; squandering; wasteful. See
        Profuse.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prodigal \Prod"i*gal\, n.
   One who expends money extravagantly, viciously, or without
   necessity; one that is profuse or lavish in any expenditure;
   a waster; a spendthrift. "Noble prodigals of life." --Trench.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prodigal
    adj 1: recklessly wasteful; "prodigal in their expenditures"
           [syn: extravagant, prodigal, profligate,
           spendthrift]
    n 1: a recklessly extravagant consumer [syn: prodigal,
         profligate, squanderer]