imˈperviously,adv. [f.prec. + -ly2.] So as to be impervious; impenetrably. 1794Sullivan View Nat. II. 293 Materials for an elucidation of a period almost imperviously involved in darkness.1866Howells Venet. Life (1883) I. vii. 111 The heavy wooden blinds [shut] imperviously.