inexcusable
UK[ˌɪnɪkˈskjuːzəbl]US[ˌɪnɪkˈskjuːzəbl]
adj
too bad to be justified or tolerated; impossible to excuse.
Morpheme Breakdown
in
excus
able
in
not
excus
to excuse
able
capable of
Etymology
the word inexcusable is built upon the foundation of the latin verb excusare, meaning "to free from blame," which itself is composed of ex- ("out of") and causa ("cause, reason"). the addition of the negative prefix in- creates a meaning of "not able to be freed from blame." the suffix -able, of latin origin, completes the construction, forming an adjective that describes a quality. thus, the literal sense of "not capable of being excused" evolved into the modern abstract meaning of something so bad that it cannot be justified or forgiven.
Analysis
Structure: in (not) + excus (to excuse) + able (capable of)
in- is a Latin prefix meaning "not". excus- is from Latin excusare, meaning "to excuse, to free from blame". -able is a suffix from Latin -abilis, forming adjectives meaning "capable of, worthy of".
Examples
his rude behavior at the dinner party was inexcusable.
the company's failure to address the safety issue is inexcusable.
there is no inexcusable delay in responding to such an urgent request.