Source : Webster's Revised Unabridged Dictionary (1913)

Mayhap \May"hap\, adv.
   Perhaps; peradventure. [Prov. or Dialectic]

Source : WordNet®

mayhap
     adv : by chance; "perhaps she will call tomorrow"; "we may
           possibly run into them at the concert"; "it may
           peradventure be thought that there never was such a
           time" [syn: {possibly}, {perchance}, {perhaps}, {maybe},
            {peradventure}]