IshDeut 123:16 :ܗ݀ܝ ܠܡ ܕܡܫܬܩܠܐ ܡܢ ܒܝܢܐ ܡܬ̈ܢܬܐ܂ ܗ݀ܝ ܕܠܥܠ ܡܢ ܐܠܝܬܐ ܩܝܡܐ ܩܠܝܠ‏ : that which is removed from between the loins, located a little bit above the tail
See the entire entry for matnān, matnātā n.f.pl.t. loins