Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sŭper-nŭmĕrārĭus, a, um, adj., supernumerary (post-class.): accensi, hoc est postea additi, quam fuisset legio completa, quos nunc supernumerarios vocant, Veg. Mil. 2, 19 fin.; Aug. in Psa. 146, 9.