Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† ăcălanthis, ĭdis, f., = ἀκαλανθίς, i. q. acanthis, a very small bird of a darkgreen color; according to Voss, the thistlefinch, goldfinch, Verg. G. 3, 338.