obsessĭo

I. a blocking up, besieging, encompassing, a blockade of a place (class.): obsessio templorum, Cic. Dom. 3, 5: militaris viae, id. Pis. 17, 40: castrorum, Suet. Caes. 58: obsessionem alicuius omittere, Caes. B. C. 3, 24 fin.