Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
euax, interj. [only Plautine], expressive of delight at some tidings or event, hail! joy! good! Plaut. Bacch. 2, 3, 13; 4, 4, 72; Cassiod. 4, 4, 13.