From Middle English attery, attry, attri, ætriȝ, from Old English ǣttriġ, ǣtriġ (“poisonous”), from Proto-Germanic *aitrīgaz (“poisonous”). Cognate with Dutch etterig (“purulent”), German eiterig (“purulent, festering”), Swedish ettrig (“poisonous”). By surface analysis, atter (“poison”) + -y.