sitiar
besiege
site
place, location
+
-ar
verb suffix
Sitiar means to besiege and can be thought of as site0 + -ar1, implying the action of surrounding a place0 (site0) to besiege it.
verb
- besiegeTo surround a place with armed forces in order to cut off outside communication and force surrender.El ejército decidió sitiar la ciudad. // The army decided to besiege the city.