Ending

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Old English endung ‘termination, completion’ (see end, -ing1).

wiktionary

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From Middle English endyng, endinge, endunge, from Old English endung, ġeendung(“ending”), equivalent to end +‎ -ing. Cognate with Dutch ending(“ending”), German Endung(“ending”).

From Middle English ending, endyng, endende, from Old English endiende, from Proto-Germanic *andijōndz, present participle of Proto-Germanic *andijōną(“to end”), equivalent to end +‎ -ing.

etymonline

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ending (n.)

"a coming to an end," early 14c., verbal noun from end (v.). Meaning "the end part (of something)" is from c. 1400. Old English had endunge "ending, end, death."