The Collaborative International Dictionary of English v.0.48:

Inception \In*cep"tion\, n. [L. inceptio, fr. incipere to begin;
   pref. in- in + capere to take. See Capable.]
   [1913 Webster]
   1. Beginning; commencement; initiation. --Bacon.
      [1913 Webster]

            Marked with vivacity of inception, apathy of
            progress, and prematureness of decay. --Rawle.
      [1913 Webster]

   2. Reception; a taking in. [R.] --Poe.
      [1913 Webster]

WordNet (r) 3.0 (2006):

inception
    n 1: an event that is a beginning; a first part or stage of
         subsequent events [syn: origin, origination,
         inception]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "inception":
   babyhood, beginning, beginnings, birth, childhood, commencement,
   conception, constitution, cradle, derivation, effectuation,
   establishment, formation, foundation, fountain, freshman year,
   genesis, grass roots, head, inauguration, inchoation, incipience,
   incipiency, incunabula, infancy, installation, institution,
   materialization, nascence, nascency, nativity, organization,
   origin, original, origination, parturition, pregnancy, provenance,
   provenience, radical, radix, realization, rise, root, setting-up,
   source, stem, stock, taproot, well, wellspring, whence, youth



Bouvier's Law Dictionary, Revised 6th Ed (1856):

INCEPTION. The commencement; the beginning. In making a will, for example,
the writing is its inception. 3 Co. 31 b; Plowd. 343. Vide Consummation;
Progression.