Yes, matrixes is a Scrabble word!

Noun

1. (mathematics) a rectangular array of quantities or expressions set out by rows and columns; treated as a single element and manipulated according to rules
2. (geology) amass of fine-grained rock in which fossils, crystals, or gems are embedded
3. An enclosure within which something originates or develops (from the Latin for womb)
4. The body substance in which tissue cells are embedded
5. The formative tissue at the base of a nail
6. Mold used in the production of phonograph records, type, or other relief surface