The Spanish verb 'sitiar' (to besiege) comes from Late Latin 'situare' meaning 'to place' or 'to besiege', which itself derives from the Latin noun 'situs' meaning 'position' or 'location'. The verb was formed with the common Spanish infinitive suffix '-ar'. The military meaning of besieging evolved from the basic concept of positioning or placing (troops) around a location to surround it.

Some related and more common Spanish words include 'sitio' (place, site), 'situar' (to place, to locate), and 'situación' (situation). All these words share the same Latin root 'situs' and maintain connections to the core meaning of position or location. While 'sitiar' specifically developed the military meaning of besieging a place, these related words kept the more general meaning of location or placement.

English speakers might recognize the connection to words like 'site', 'situation', and 'situate', which all come from the same Latin root 'situs'. While the Spanish 'sitiar' took on the specific meaning of besieging, these English cognates maintained meanings more closely related to the original sense of location or position. The word 'site' in particular is a direct descendant of Latin 'situs'.