'infrequently-confirmed' is a modern compound formed from 'infrequently' and 'confirmed'. 'Infrequently' derives from 'in-' + 'frequent' + '-ly' (negative/degree prefix + Latin-rooted adjective + adverbial suffix), while 'confirmed' comes from Latin 'confirmare' via Old French and Middle English.

'infrequently' developed in English from Latin 'frequens/frequent-' (through Old French and Middle English) plus the adverbial suffix '-ly'; 'confirmed' changed from Latin 'confirmare' to Old French 'confermer' and Middle English 'confirmen', leading to modern English 'confirm' and past participle 'confirmed'. The compound itself is a recent English formation combining the adverb-derived modifier with the past-participial adjective.

Individually, 'infrequently' originally meant 'not occurring often' and 'confirm' meant 'to make firm or certain'; together as a compound the phrase has come to mean 'made certain only rarely' or 'seldom verified'.