IshGen 24:11 :ܪܩܝܥܐ ܩܪܝܗܝ ܡܛܠ ܕܡ݂ܢ ܟܝܢܐ ܪܦܝܐ ܕܡܝ̈ܐ ܐܬܪܩܥ ܘܐܫܬܪܪ‏ : He called it "firmament" because it was tightened and made firm from the loose nature of the water
See the entire entry for šrr vb. to be firm, true