The Collaborative International Dictionary of English v.0.48:

T \T\ (t[=e]),
   the twentieth letter of the English alphabet, is a nonvocal
   consonant. With the letter h it forms the digraph th, which
   has two distinct sounds, as in thin, then. See Guide to
   Pronunciation, [sect][sect]262-264, and also [sect][sect]153,
   156, 169, 172, 176, 178-180.
   [1913 Webster] The letter derives its name and form from the
   Latin, the form of the Latin letter being further derived
   through the Greek from the Ph[oe]nician. The ultimate origin
   is probably Egyptian. It is etymologically most nearly
   related to d, s, th; as in tug, duke; two, dual, L. duo;
   resin, L. resina, Gr. "rhti`nh, tent, tense, a., tenuous,
   thin; nostril, thrill. See D, S.
   [1913 Webster]

   T bandage (Surg.), a bandage shaped like the letter T, and
      used principally for application to the groin, or
      perineum.

   T cart, a kind of fashionable two seated wagon for pleasure
      driving.

   T iron.
   (a) A rod with a short crosspiece at the end, -- used as a
       hook.
   (b) Iron in bars, having a cross section formed like the
       letter T, -- used in structures.

   T rail, a kind of rail for railroad tracks, having no
      flange at the bottom so that a section resembles the
      letter T.

   T square, a ruler having a crosspiece or head at one end,
      for the purpose of making parallel lines; -- so called
      from its shape. It is laid on a drawing board and guided
      by the crosspiece, which is pressed against the straight
      edge of the board. Sometimes the head is arranged to be
      set at different angles.

   To a T, exactly, perfectly; as, to suit to a T. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

to a T
    adv 1: in every detail; "the new house suited them to a T" [syn:
           to a T, to the letter, just right, to perfection]