1548, from M.Fr.
sagacité, from L.
sagacitatem (nom.
sagacitas) "quality of being acute," from
sagax (gen.
sagacis) "of quick perception," related to
sagus "prophetic,"
sagire "perceive keenly," from PIE base
*sag- "to track down, trace, seek" (cf. O.E.
secan "to seek;" see
seek). Also used 17c.-18c. of animals, meaning "acute sense of smell."