Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
antĕ-mūrāle, is, n., a protecting wall, an outwork, breastwork (eccl. Lat.), Hier. Hom. 2: murus et antemurale, Vulg. Isa. 26, 1: luxitque antemurale, ib. Thren. 2, 8.