rŏtundātĭo: ōnis, f. rotundo,I a making round, a rounding: linea rotundationis, i. e. the circumference, Vitr. 1, 6 fin.; 3, 1; 10, 11.
rŏtundātĭō, ōnis, f. (rotundo), action d’arrondir, forme circulaire : Vitr. Arch. 1, 6.