Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
circāmoerĭum, ii, n. [circa-moerus, for murus; cf. pomerium], the space about a wall, on both sides of a wall: pomerium, verbi vim solam intuentes, postmoerium interpretantur esse; est autem magis circamoerium, Liv. 1, 44, 4.