Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
circum-sĭlĭo, īre, v. n. [salio], to spring, leap, or hop around (rare): (passer) circumsiliens modo huc, modo illuc, * Cat. 3, 9.
Trop., to leap about, surround: morborum omne genus, * Juv. 10, 218.