Boo de Piélagos

The second element is the clearer. Pelagus, from the Greek πέλαγος ('open sea, deep sea'), entered learned Latin as a nautical Hellenism —⁠Pliny, Tacitus, Virgil use it to distinguish the open sea from the coastal littoral. In Hispanic toponymy it specialised to designate wide zones of water, particularly broad estuaries or inland sea arms. The plural noun piélagos in old Castilian referred to 'the seas, the deep waters'. The Cantabrian region of Piélagos takes its name from the wide estuaries of the Pas river, navigable until the late Middle Ages. The first element Boo is more problematic: Cantabrian onomastics has proposed opaque pre-Roman bases, unidentified medieval anthroponyms and derivation from the Latin bovis ('ox') in adjectival function, without any reading prevailing. The hamlet belongs to the Piélagos council and preserves the Romanesque parish church of San Lorenzo from the 13th century.