The Collaborative International Dictionary of English v.0.48:

Formalize \Form"al*ize\, v. i.
   To affect formality. [Obs.] --ales.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Formalize \Form"al*ize\ (f[^o]rm"al*[imac]z), v. t. [imp. & p.
   p. Formalized (f[^o]rm"al*[imac]zd); p. pr. & vb. n.
   Formalizing (f[^o]rm"al*[imac]`z[i^]ng).]
   1. To give form, or a certain form, to; to model. [R.]
      [1913 Webster]

   2. To render formal.
      [1913 Webster]

WordNet (r) 3.0 (2006):

formalize
    v 1: make formal or official; "We formalized the appointment and
         gave him a title" [syn: formalize, formalise]
    2: declare or make legally valid [syn: validate, formalize,
       formalise] [ant: annul, avoid, invalidate, nullify,
       quash, void]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "formalize":
   agree on terms, block out, carve, cast, celebrate, chisel, codify,
   conventionalize, create, cut, dignify, efform, fashion, figure,
   fix, forge, form, found, frame, hew, knead, knock out, lay out,
   lick into shape, mint, model, mold, normalize, observe, regularize,
   ritualize, rough out, roughcast, roughhew, sculpt, sculpture, seal,
   set, shake hands, shape, sign, solemnize, stamp, standardize,
   strike a bargain, stylize, tailor, thermoform, work