Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
‡ 1. mergŭlus, i, m. [mergo], the wick of a lamp: mergulus, ἐλλύχνιον, Gloss. Gr. and Lat.
2. mergŭlus, i, m. dim. [mergus], a diver, a kind of bird, Vulg. Lev. 11, 17; id. Deut. 14, 17.