Meaning of GROUND in English
( n. )
That surface upon which the figures of a composition are set, and which relieves them by its plainness, being either of one tint or of tints but slightly contrasted with one another; as, crimson Bowers on a white ground.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012