Ma'trixz (ma'triks; mat'riks), n.; pl. MATRICES (ma'tri·sez; mat'ri-; rarely, ma·tri'sez); MATRIXEZ (ma'trik-sez; -siz; mat'rik-).[L] A place or enveloping element within which something originates, takes form or develops. The natural material in which any metal, fossil, pebble, crystal, or gem is embedded. That which gives form, origin, or foundation to something enclosed or embedded in it