| Subject | English | Welsh |
| comp., MS | complex number | rhif cymhleth (A number in the form a + bi, where a and b are real numbers and i = sqrt(-1) , so that bi is imaginary unless b = 0) |
| comp., MS | complex script | sgript gymhleth (A language whose characters require ligation or shaping, such as a right-to-left language (Arabic, Persian, Hebrew, and Urdu) or certain South Asian languages) |