Both jisho.org and Wikipedia have ドットマトリクス for dot matrix (printer), but I've tried using it on a couple of middle-aged people and they didn't understand it. Maybe I've mispronounced it, or overestimated people's ages, or their ability to know computer terminology, but is ドットマトリクス correct, or should I be using something else?
ドットマトリクス is an established word, but unfortunately only among mechanical engineers. I'm not very sure how common the word is in English, but I can confirm that it's anything but what you'd hear from lay people in Japan.
If you want them to grasp the concept of dot matrix, I think you can only explain it: 電光掲示板のような, 古いレシートのような, 絨毯の織り目のような, 点描画のような, 点を並べて作る etc. according to what they're familiar with.