Instead

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Middle English (originally as two words): from in + stead.

wiktionary

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in +‎  stead, from Middle English ine(“in”) +  stede(“stead”). Related to German statt. 

etymonline

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instead (adv.)

1590s, contraction of Middle English prepositional phrase ine stede (early 13c.; see stead), itself a loan-translation of Latin in loco (French en lieu de). Typically written as two words until mid-17c.