n. & v.
n. (also flagstone) 1 a flat usu. rectangular stone slab used for paving. 2 (in pl.) a pavement made of these.
v.tr. (flagged, flagging) pave with flags.
[ ME, = sod: cf. Icel. flag spot from which a sod has been cut out, ON flaga slab of stone, and FLAKE(1) ]