Source : Webster's Revised Unabridged Dictionary (1913)

Proverbial \Pro*ver"bi*al\, a. [L. proverbialis: cf. F.
   proverbial.]
   1. Mentioned or comprised in a proverb; used as a proverb;
      hence, commonly known; as, a proverbial expression; his
      meanness was proverbial.

            In case of excesses, I take the German proverbial
            cure, by a hair of the same beast, to be the worst.
                                                  --Sir W.
                                                  Temple.

   2. Of or pertaining to proverbs; resembling a proverb. ``A
      proverbial obscurity.'' --Sir T. Browne.

Source : WordNet®

proverbial
     adj 1: of or relating to or resembling or expressed in a proverb;
            "he kicked the proverbial bucket"; "the proverbial
            grasshopper"
     2: widely known and spoken of; "her proverbial lateness"; "the
        proverbial absentiminded professor"; "your proverbial
        dizzy blonde"