IshGen 176:18 :ܐܥܝܦܬܐ ܗܢܘ܂ ܡܥܪܬܐ ܕܐܝܬ ܠܓܘ ܡܢܗ݀ ܬܘܒ ܡܥܪܬܐ‏ : "double", i.e., a cave with another cave inside of it
See the entire entry for maˁrā, mˁarṯā n.f. cave