According to Terry and Gant, can a person be searched without there also necessarily being a seizure?

According to Terry and Gant, can a person be searched without there also necessarily being a seizure? In other words, constitutionally, can there be a lawful search without some sort of seizure occurring beforehand? Can there ever be a seizure absent an arrest? Can there ever be a lawful arrest absent a warrant? Can there ever be a search without a warrant? Under what circumstances, if any, may a seizure occur without an arrest?