Having reached full natural growth or development: a mature cell. Having reached a desired or final condition; ripe: a mature cheese. Of, relating to, or characteristic of full development, either mental or physical: mature for her age. Suitable or intended for adults: mature subject matter. Composed of adults: a mature audience. Worked out fully by the mind; considered: a mature plan of action. Having reached the limit of its time; due: a mature bond. No longer subject to great expansion or development. Used of an industry, a market, or a product. Geology Having reached maximum development of form. Used of streams and landforms. To bring to full development; ripen. To work out fully in the mind: "able to digest and mature my thoughts for my own mind only\u201d ( John Stuart Mill). To evolve toward or reach full development: The child's judgment matures as she grows older. To become due. Used of notes and bonds.