Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† mĕtaplastĭcōs, adv., = μεταπλαστικῶς, metaplastically, by the use of metaplasm: metaplasticos dicitur apud poëtas usurpari id quod propter necessitatem metri mutare consueverunt, Paul. ex Fest. p. 153 Müll.