irrespirable

Either: * from ir- (prefix meaning ‘not’) + respirable; or * borrowed from French irrespirable, from Late Latin irrespīrābilis, from Latin ir- (a variant of in- (prefix meaning ‘not’)) + respīrāre + -ābilis (suffix meaning ‘able to be’). Respīrāre is the present active infinitive of respīrō (“to blow or breathe back; to breathe, respire; to breathe out, exhale”), from re- (prefix meaning ‘again; back, backwards’) + spīrō (“to blow; to breathe, respire; to breathe out, exhale”) (ultimately from Proto-Indo-European *(s)peys- (“to blow; to breathe”)).

来源：wiktionary