(ˈ)im, əm+ adjective
Etymology: Late Latin impermeabilis, from Latin in- in- (I) + Late Latin permeabilis permeable — more at permeable
: not permeable : not permitting passage (as of a fluid) through its substance : impassable , impervious
an impermeable stone
a coat impermeable to rain
an impermeable layer of scum
• im·permeableness “+ noun
• im·permeably “+ adverb