noun

• (now rare) The womb.
  "upon conception the inward orifice of the matrix exactly closeth, so that it commonly admitteth nothing after […]"
• (biology) The material or tissue in which more specialized structures are embedded.
• (biology) An extracellular matrix, the material or tissue between the cells of animals or plants.
• (biology) Part of the mitochondrion.

name

• (science fiction) A simulated reality to which many humans are connected. In some works created by sentient machines to subdue humans.
  "“The matrix has its roots in primitive arcade games,” said the voice-over, “in early graphics programs and military experimentation with cranial jacks.” […] “Cyberspace. A consensual hallucination experienced daily by billions of legitimate operators, in every nation, by children being taught mathematical concepts … A graphic representation of data abstracted from the banks of every computer in the human system. Unthinkable complexity. […]”"
• (figurative) A social institution or apparatus perceived as largely deceptive or illusory.
  "They claimed that Paraguay’s accommodating immigration laws have proved attractive to Germans who want to “escape the matrix” and flee the “deep state and one world order”."