What is Ambulatory?

Legal Definition
The ambulatory (Latin: ambulatorium, lit. "walking place") is the covered passage around a cloister or the processional way around the east end of a cathedral or large church and behind the high altar.

The term is also used to describe a garden feature in the grounds of a country house. A typical example is the one shown, which stands in the grounds of Horton Court in Gloucestershire, UK.
-- Wikipedia
Legal Definition
Movable; revocable; subject to change. Ambulatoria voluntas (a changeable will) denotes the power which a testator possesses of altering his will during his llfe-time. Hattersley v. Bissett, 50 N. J. Eq. 577, 25 All. 332 The court of king's bench in England was formerly called an "ambulatory court," because it followed the king's person, and was held sometimes In one place and sometimes in another. So, in France, the supreme court or parliament was originally ambulatory. 3 BL Comm. 38, 39, 41. The return of a sheriff has been said to be ambulatory until it ls filed. Wilmot, J., 3 Burr. 1644.
-- Black's Law Dictionary