Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† ŏrīgănum and -on, i, n., and ŏrī-gănus, i, m., = ὀρείγανον, ὀρίγανον, and ὀρείγανος, or ὀρίγανος, the plant wild-marjoram, origan, Plin. 20, 17, 67, § 175; Ser. Samm. 47, 879.