Inexcusably

[ɪnɪk'skjʊzəbli]

(adv.) in an unpardonable manner or to an unpardonable degree; 'he was inexcusably cruel to his wife'.

Inputed by Ethel--From WordNet

(adv.) With a degree of guilt or folly beyond excuse or justification.

Typed by Edwina

Well or ill done, excusably or inexcusably, it was done. Charles Dickens. Great Expectations.
The forewoman was right: the sewing on of the spangles was inexcusably bad. Edith Wharton. The House of Mirth.

Typed by Edwina