The Collaborative International Dictionary
Impierceable
Impierceable \Im*pierce"a*ble\ ([i^]m*p[=e]rs"[.a]*b'l) a.
Not capable of being pierced; impenetrable. [Obs.]
--Spenser.
Wiktionary
impierceable
a. (context obsolete English) Not capable of being pierced; impenetrable.