The Collaborative International Dictionary
Penetrably
Penetrable \Pen"e*tra*ble\, a. [L. penetrabilus: cf. F. p['e]n['e]trable.] Capable of being penetrated, entered, or pierced. Used also figuratively.
And pierce his only penetrable part.
--Dryden.
I am not made of stones,
But penetrable to your kind entreats.
--Shak.
[1913 Webster] -- Pen"e*tra*ble*ness, n. --
Pen"e*tra*bly, adv.
Wiktionary
penetrably
adv. In a penetrable way.