riddance n.

c. 1200, ridden, "clear (a space); set free, save," from Old English *ryddan (past participle geryd) or else from a Scandinavian source akin to Old Norse ryðja (past tense ruddi, past participle ruddr) "to clear (land) of obstructions," from Proto-Germanic *reudijan (source also of Old High German riuten, German reuten "to clear land," Old Frisian rothia "to clear," Old English -royd "clearing," common in northern place names), from PIE root *reudh- "to clear land."

Meaning "be rid of, be freed from" (something troublesome or useless) is from mid-15c. The general sense of "to make (someone or someplace) free (of someone or something else)" emerged by 16c. The senses have merged somewhat with those in Northern English, Scottish, and U.S. dialectal redd (q.v.). To get rid of (something or someone) is from 1660s. Related: Ridden; ridding.

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, from PIE *-nt-, adjectival suffix.

Latin present-participle endings for verbs stems in -a- were distinguished from those in -i- and -e-. Hence Modern English protestant, opponent, obedient from Latin protestare, opponere, obedire.

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).

English thus inherited a confused mass of words from French (crescent/croissant), and further confused it since c. 1500 by restoring -ence selectively in some forms of these words to conform with Latin. Thus dependant, but independence, etc.