Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* ex-jūro, āvi, 1, v. a., to swear solemnly, Plaut. Fragm. ap. Non. 105, 22. (The line, Plaut. Am. 3, 3, 18, found in some edd. is spurious.)