Adverb
With a degree of guilt or folly beyond excuse or justification.
Source: Webster's dictionaryWhen so many are lonely as seem to be lonely, it would be inexcusably selfish to be lonely alone. Tennessee Williams
The universe is almost 14 billion years old, and, wow! Life had no problem starting here on Earth! I think it would be inexcusably egocentric of us to suggest that we're alone in the universe. Neil deGrasse Tyson
To succeed in science, you have to avoid dumb people (here I was still following Luria's example). Now that might sound inexcusably flip, but the fact is that you must always turn to people who are brighter than yourself. James D. Watson
he is unjustifiably harsh on her Source: Internet
he was inexcusably cruel to his wife Source: Internet
Annie Clark, a spokesperson for Collins' campaign, in a statement criticized Gideon for not doing enough in the legislature on Covid-19 response, accusing her of having been “inexcusably on the sidelines” to campaign. Source: Internet