Neck of a guitar; Where the neck has been scalloped.
Usually found on Lutes. When the fret has been scalloped (grooved) from one fret wire to the other (through the whole neck).
Yngwie Malmsteen popularized this spec with his Signature Fender Start. The neck it self can cost up to $900.
If taken to a local shop can be done for around $300 on a stock neck.
Richie Blackmore also had a similar guitar.
It does not allow you to play faster (in fact its harder to play, and get used to) Although bending and vibratto is performed better. Once one learns to play well on a scalloped neck, a regular neck will be easier to play than before.
guitar player: "Dude i scalloped the neck of my guitar"
guitar teacher: "Wholy motherfucker! That is the coolest thing ever! Let me see it... OMG!"