Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
circum-lŭo, ĕre, v. a., to flow around or wash upon (rare): Rhenus tergum ac latera circumluit, Tac. H. 4, 12: pars arcis circumluitur mari, Liv. 25, 11, 1: litora subit et circumluit pelagus, Mel. prooem. 2: (Aegeum) mare laevā Imbrum et Tenedum circumluens, Amm. 22, 8, 2.