From The Collaborative International Dictionary of English v.0.48 [gcide]:
Mayhap \May"hap\, adv.
Perhaps; peradventure. [Prov. or Dialectic]
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
mayhap
adv 1: 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,
mayhap, peradventure]