'Mayhap' is an Olde Englishe word meaning 'perhaps'. It is a portmanteau word created from "It May Happen".
It was a prescient piece of town-planning that gave it its name. As the story begins, it appears that the street isn't actually there, as shown by this dialogue:
- "Still not turned up, has it?"
- "There is nothin' the matter with Mayhap Street, Dean," said Ridcully sharply. "It is merely temporarily displaced, that's all. I am assured the rest of the continuum will catch up with it no later than Thursday. It was an accident that was waiting to happen."
- "Well, only waiting for a thaumic discharge that happened because you said there was no way it could possibly..." the Dean began.
Ridcully brings this conversation to an abrupt end shortly afterwards.
'Mayhap' the street has turned up since - it has not been named again.