- A situation or surrounding substance within which something else originates, develops, or is contained: "Freedom of expression is the matrix, the indispensable condition, of nearly every form of freedom” ( Benjamin N. Cardozo).
- The womb.
- Anatomy The formative cells or tissue of a fingernail, toenail, or tooth.
- Anatomy See ground substance.
- Geology The solid matter in which a fossil or crystal is embedded.
- Geology Groundmass.
- A mold or die.
- The principal metal in an alloy, as the iron in steel.
- A binding substance, as cement in concrete.
- Mathematics A rectangular array of numeric or algebraic quantities subject to mathematical operations.
- Something resembling such an array, as in the regular formation of elements into columns and rows.
- Computer Science The network of intersections between input and output leads in a computer, functioning as an encoder or a decoder.
- Printing A mold used in stereotyping and designed to receive positive impressions of type or illustrations from which metal plates can be cast. Also called mat2.
- Printing A metal plate used for casting typefaces.
- An electroplated impression of a phonograph record used to make duplicate records.