P Job38:30 :ܐܝܟ ܟܐ̈ܦܐ ܡܬܩܫܝܢ ܡ̈ܝܐ ܘܐ̈ܦܝ ܬܗ̈ܘܡܐ ܐܚܕܝܢ‏ : the water becomes as hard as rocks and they lock up the surface of the deeps
See the entire entry for thōm, thōmā n.m. abyss