A forward-swept wing or reverse-swept wing is an aircraft wing configuration in which the quarter-chord line of the wing has a forward sweep. Typically, the leading edge also sweeps forward.
Forward-swept wing of the Sukhoi Su-47
LET L-13 two-seat glider
ARV Super2
Grumman X-29 displaying forward-swept wing configuration
The wing configuration of a fixed-wing aircraft is its arrangement of lifting and related surfaces.
The Spitfire wing may be classified as: "a conventional low-wing cantilever monoplane with unswept elliptical wings of moderate aspect ratio and slight dihedral".