Adequate

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early 17th century: from Latin adaequatus ‘made equal to’, past participle of the verb adaequare, from ad- ‘to’ + aequus ‘equal’.

wiktionary

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Latin adaequatus, past participle of adaequare(“to make equal to”); ad + aequare(“to make equal”), aequus(“equal”).

etymonline

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adequate (adj.)

1610s, "equal to what is needed or desired, sufficient," from Latin adaequatus "equalized," past participle of adaequare "to make equal to, to level with," from ad "to" (see ad-) + aequare "make level," from aequus "equal, even" (see equal (adj.)). The sense is of being "equal to what is required." It shares duty with enough, depending on the subject. With a slightly disparaging tinge, "mediocre, just good enough," by 1900. Related: Adequateness.