per-sīdo, sēdi, sessum, 3, v. n.,
to sink or settle down , to penetrate anywhere (poet.): pestilitas fruges persidit in ipsas, Lucr. 6, 1126; 1, 307: ubi frigidus imber Altius ad vivum persedit, Verg. G. 3, 442.
per-sīdō sēdī, —, ere, to sink down, penetrate: Altius ad vivum, V. ...
An Elementary Latin Dictionary