CPAHor 440:15 :ܬ݁ܠܝܬ݁ܝܘܬܐ ܕܠܝܬ ܠܗ ܫܘܪܝ܃ ܐܘܣܝܐ ܕܠܐ ܡܬ݁ܦܠܓܐ‏ : the Trinity without beginning, the indivisible essence
See the entire entry for tlīṯāyū, tlīṯāyūṯā n.f. trinity