A quick google shows it to be a very old word. The modern equivalent would be a close approoximation to the verb 'to encompass' Compasseth seems to be used in a geographical sense, indicating an area of land, and the 'compass' element giving it a sense of a surrounding area, or an enclosure.

It means to surround. It is an old English form of the word "encompasses". To encompass means to surround from all directions.

Livia, If you post the word in a sentence we can give you the exact meaning. compasseth = archaic English third-person singular simple present form of " to compass". -he, she, it compasseth The verb "to compass" still exists today. Here are a few of its modern definitions. 1) To surround; to encircle; to environ; to stretch round. 2) To go about or round entirely; to traverse. 3) To accomplish; to reach; to achieve; to obtain. 4) To plot; to scheme (against someone).