My method for answering this kind of question--phrase or terminology translation--is: 1) Go to the English Wikipedia, and see if there is an article about it. In this case, there is: https://en.wikipedia.org/wiki/Mousepad 2) Look toward the left edge of the screen, to see if there are articles about the same thing in the target language. In this case, there is: https://es.wikipedia.org/wiki/Alfombrilla_de_ratón 3) Read a bit of the article, to see what it says about terminology in the opening sentences: "La 'alfombrilla de ratón,' 'alfombrilla posa ratón,' 'almohadilla de ratón' o 'mousepad'..." I find this very useful for all kinds of questions like names of technical fields, place names (should "Carson City" be "Ciudad Carson?" Answer: no. Should "New Orleans" be "Nueva Orleans?" Answer: yes.)

En Argentina le decimos pad.

It is 🙂!