From Middle English etlien, atlien, from Old Norse ætla ("to think, mean, suppose, intend, purpose"), from Proto-Germanic *ahtalōną ("to strive, think"), from Proto-Indo-European *ok- ("to think, intend, purpose"); partly from Middle English aghtelen, ahtlien, from a frequentative variant of Old English eahtian ("to estimate, esteem, fix the character or quality of something, consult about, consider, deliberate, mediate, devise, watch over, speak of with praise"), from Proto-West Germanic *ahtōn ("to think, believe, fear"), from Proto-Germanic *ahwjaną ("to believe, intend, think, fear"), from Proto-Indo-European *okʷ-, *h₃ekʷ-.
Cognate with Dutch achten ("to deem, regard, esteem, think"), German achten ("to heed, respect, value"), Danish agte ("to esteem, intend, observe, heed"), Gothic 𐌰𐌷𐌾𐌰𐌽 ("to think"). More at eye.