Altogether

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Old English(see all, together).

wiktionary

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From Middle English altogeder, altogedere, equivalent to al-(“all”) +‎ together. Cognate with Scots awthegither(“altogether”), Middle High German alzegater(“altogether”). Compare also Old English ealġeador, eallġeador(“altogether”), West Frisian allegearre(“altogether”). More at together.

The noun sense (nakedness): was popularized in George du Maurier's 1894 novel Trilby.

etymonline

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altogether (adv.)

"wholly, entirely, completely," early 13c., altogedere, a strengthened form of all (also see together); used in the sense of "a whole" from 1660s. OED notes, "There is a common tendency to write altogether where all together is logically preferable," and gives examples from 1765. The altogether "a condition of nakedness" is from 1894.