in logic, the mean or middle term of a syllogism, being an argument, reason, or consideration for which we affirm or deny any thing: or, it is the cause why the greater extreme is affirmed or denied of the less in the conclusion.

arithmetic, or arithmetical medium, or mean, that which is equally distant from each extreme, or which exceeds the lesser extreme as much as it is exceeded by the greater, in respect of quantity not of proportion: thus 9 is a medium between 6 and 12.

philosophy, that space or region through which a body in motion passes to any point - thus air, is the medium wherein bodies move near our earth; water, the medium wherein fishes live and move; and glass is also a medium of light, as it affords it a free passage. That density or consistence in the parts of the medium, whereby the motion of bodies in it is retarded, is called the resistance of the medium; which together with the force of gravity, is the cause of the cessation of the motion of projectiles.

Subtile or aetherial Medium. See Ether.