Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prae-ungo, no perf., unctum, 3, v. a., to smear or anoint before (post-class.): praeungendum est vulnus, Theod. Prisc. 1, 19: digitus praeunctus adipe anserino, Cael. Aur. Tard. 4, 3, 45.