a-(on) + ground

source: By Hillebrand Steve, U.S. Fish and Wildlife Service - http://www.public-domain-image.com/public-domain-images-pictures-free-stock-photos/transportation-vehicles-public-domain-images-pictures/ships-boats-public-domain-images-pictures/cargo-ship-aground.jpg, Public Domain

(with reference to a ship) on or onto the bottom in shallow water:

〖be ～〗 〈船などが〉座礁して

e.g. as adverb : the ships must slow to avoid running aground

e.g. as predicative adjective : a cargo ship aground in the Mediterranean.

Middle English (in the sense ‘on the ground’): from a-2 ‘on’ + ground1.