I sometimes excuse my français when I get frustrated and speak more bluntly than intended.

When I accidentally cursed in front of my colleagues, I had to excuse my Francais and apologize.

When teaching students arithmetic, I say please excuse my dear Aunt Sally to help them remember the order of operations.

He excuseth the late arrival by citing an unavoidable accident.

If thou excusest my careless words, I shall strive to be more mindful henceforth.

His excuseless failure to report the leak caused severe damage.

His excuselessness in the matter left even his closest friends speechless.