Definify.com

Webster 1913 Edition

adv.

With a degree of guilt or folly beyond excuse or justification.

Inexcusably

obstinate and perverse.

Jortin.

adv.

With a degree of guilt or folly beyond excuse or justification.

inexcusably ‎(comparative more inexcusably, superlative most inexcusably)

in an inexcusable manner