Saltire

[Tina]

[The flag] of the greatest country on earth, SCOTLAND. Originated in Greece with the death of St.Andrew on a x-shaped cross, but made famous when the Picts and [Scots] united in battle to see the English defeated under cross-shaped clouds on a [blue sky].

[Kit]

(of a design) incorporating a motif based on a saltire cross.

[Dave Paprocki]

a diagonal X-shaped cross, for example on a flag