Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
The word DEIERATIO could not be parsed. Trying a normal dictionary lookup:
dējĕrātio, ōnis, f., v. dejuratio.
dējūrātĭo (dējĕr-), ōnis, f. [dejuro], an oath (post-class.): testari sub dejuratione (al. dejeratione), Tert. Poenit. 4: DEIERATIO ESTO APVD MAGISTRATOS, Inscr. Fratr. Arv. ap. Marin. p. 70.