[also, after Terry Pratchett, pointy
hat] Notional headgear worn by whoever is the
wizard in a particular context. The implication is
that it's a transferable role. Talk to Alice, she's wearing the
TCP/IP wizard hat while Bob is on vacation.
This metaphor is
sufficiently live that one may actually see hackers miming the act of
putting on, taking off, or transferring a phantom hat. See also
pointy hat, compare
patch pumpkin.