cir·cum·val·late 
(sûr′kəm-vălāt′)
(sûr′kəm-vălāt′)tr.v. cir·cum·val·lat·ed, cir·cum·val·lat·ing, cir·cum·val·lates
To surround with or as if with a rampart.
adj.
1. (also -ĭt) Surrounded with or as if with a rampart.
2. Anatomy Surrounded by a ridge or raised, wall-like structure.
[Latin circumvallāre, circumvallāt- : circum-, circum- + vallum, rampart with palisades (from vallus, post, stake).]
cir′cum·val·lation n.