Source : Webster's Revised Unabridged Dictionary (1913)

True-blue \True"-blue`\, a.
   Of inflexible honesty and fidelity; -- a term derived from
   the true, or Coventry, blue, formerly celebrated for its
   unchanging color. See {True blue}, under {Blue}.

True-blue \True"-blue`\, n.
   A person of inflexible integrity or fidelity.

Source : WordNet®

true-blue
     adj : marked by unswerving loyalty; "a true-blue American"; "a
           reliable true-blue country club conservative"