NOUN (1)

1. the first letter of a word (especially a person's name);
- Example: "he refused to put the initials FRS after his name"


VERB (1)

1. mark with one's initials;


ADJECTIVE (1)

1. occurring at the beginning;
- Example: "took the initial step toward reconciliation"

The Collaborative International Dictionary of English v.0.48:

Initial \In*i"tial\, a. [L. initialis, from initium a going in,
   entrance, beginning, fr. inire to go into, to enter, begin;
   pref. in- in + ire to go: cf. F. initial. See Issue, and
   cf. Commence.]
   [1913 Webster]
   1. Of or pertaining to the beginning; marking the
      commencement; incipient; commencing; as, the initial
      symptoms of a disease.
      [1913 Webster]

   2. Placed at the beginning; standing at the head, as of a
      list or series; as, the initial letters of a name.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Initial \In*i"tial\, n.
   The first letter of a word or a name.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Initial \In*i"tial\, v. t. [imp. & p. p. Initialed; p. pr. &
   vb. n. Initialing.]
   To put an initial to; to mark with an initial of initials.
   [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

initial
    adj 1: occurring at the beginning; "took the initial step toward
           reconciliation"
    n 1: the first letter of a word (especially a person's name);
         "he refused to put the initials FRS after his name"
    v 1: mark with one's initials

Moby Thesaurus II by Grady Ward, 1.0:

129 Moby Thesaurus words for "initial":
   OK, abecedarian, aboriginal, accept, accredit, affirm, alpha,
   alphabet, alphabetize, amen, antecedent, antenatal, approve,
   authenticate, authorize, autochthonous, autograph, basic,
   beginning, breaking-in, budding, capitalize, certify, character,
   commencing, confirm, cosign, countersign, creative, earliest,
   early, elemental, elementary, embryonic, endorse, fetal, first,
   first blush, first glance, first impression, first inning,
   first lap, first move, first round, first sight, first stage,
   first step, foremost, formative, foundational, fundamental, gambit,
   germinal, gestatory, give permission, give the go-ahead,
   give the imprimatur, give thumbs up, headmost, in embryo,
   in its infancy, in the bud, inaugural, inceptive, inchoate,
   inchoative, incipient, incunabular, infant, infantile, initiative,
   initiatory, inscribe, introductory, inventive, le premier pas,
   leading, letter, maiden, mark, monogram, nascent, natal, notarize,
   opening, opening move, original, parturient, pass, pass on,
   pass upon, permit, pioneer, postnatal, pregnant, prenatal, primal,
   primary, prime, primeval, primitive, primitiveness, primitivity,
   primogenial, procreative, ratify, rubber stamp, rudimental,
   rudimentary, sanction, say amen to, seal, second, sign,
   sign and seal, subscribe to, support, swear and affirm, swear to,
   transcribe, transliterate, undersign, underwrite, ur, validate,
   visa, vise, warming-up, warrant



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

INITIAL. Placed at the beginning. The initials of a man's name are the first
letters of his Dame; as, G. W. for George Washington. When in a will the
legatee is described by the initials of his name only, parol evidence may be
given to prove his identity. 3 Ves. 148. And a signature made simply with
initials is binding. 1 Denio, R. 471. But see Ersk. Inst. B. 3, t. 2, n. 8.