-ance

word-forming element attached to verbs to form abstract nouns of process or fact (convergence from converge), or of state or quality (absence from absent); ultimately from Latin -antia and -entia, which depended on the vowel in the stem word.

As Old French evolved from Latin, these were leveled to -ance, but later French borrowings from Latin (some of them subsequently passed to English) used the appropriate Latin form of the ending, as did words borrowed by English directly from Latin (diligence, absence).