The Collaborative International Dictionary of English v.0.48:

Realization \Re`al*i*za"tion\ (r[=e]`al*[i^]*z[=a]"sh[u^]n), n.
   [Cf. F. r['e]alisation.]
   The act of realizing, or the state of being realized.
   [1913 Webster]

WordNet (r) 3.0 (2006):

realization
    n 1: coming to understand something clearly and distinctly; "a
         growing realization of the risk involved"; "a sudden
         recognition of the problem he faced"; "increasing
         recognition that diabetes frequently coexists with other
         chronic diseases" [syn: realization, realisation,
         recognition]
    2: making real or giving the appearance of reality [syn:
       realization, realisation, actualization,
       actualisation]
    3: a musical composition that has been completed or enriched by
       someone other than the composer [syn: realization,
       realisation]
    4: a sale in order to obtain money (as a sale of stock or a sale
       of the estate of a bankrupt person) or the money so obtained
       [syn: realization, realisation]
    5: the completion or enrichment of a piece of music left
       sparsely notated by a composer [syn: realization,
       realisation]
    6: something that is made real or concrete; "the victory was the
       realization of a whole year's work" [syn: realization,
       realisation, fruition]

The Free On-line Dictionary of Computing (19 January 2023):

realization

    A UML semantic relationship between a
   classifier that specifies a contract and another classifier
   that guarantees to carry it out.

   [Handout by Mr. David Gillibrand].

   (2007-03-15)