ward-corn

from The Century Dictionary.

• noun In old English law, the duty of keeping watch and ward in time of danger, with the duty of blowing a horn on the approach of a foe.

from the GNU version of the Collaborative International Dictionary of English.

• noun (O. Eng. Law) The duty of keeping watch and ward (see the Note under watch, n., 1) with a horn to be blown upon any occasion of surprise.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun UK, law, obsolete The duty of keeping watch and ward, with a horn to be blown upon any occasion of surprise.