1. The conducting of liquid through a channel or pipe. Now chiefly applied to natural processes, e.g. the movement of sap in plants.
2. The transfer of heat between two parts of a stationary system, caused by a temperature difference between the parts.
3. The transmission or conveying of something through a medium or passage, especially the transmission of electric charge or heat through a conducting medium without perceptible motion of the medium itself.
4. The carrying of sound waves, electrons, heat, or nerve impulses by a nerve or other tissue in the body.

A form of aphasia in which the patient understands spoken and written words, is aware of his deficit, and can speak and write, but skips or repeats words, or substitutes one word for another (paraphasia).

Word repetition is severely impaired.

1. The passage of an electric charge that can occur by a variety of processes; such as, the passage of electrons or ionized atoms.
2. The passage of electric charges because of a force exerted on them by an electric field.

Conductivity is the measure of the ability of a conductor to carry electric current and it is defined as the ratio of the amount of charge passing through unit area of the conductor (perpendicular to the current direction) per second divided by the electric field intensity (the force on a unit charge).

Conductivity is the reciprocal of resistivity and it is therefore commonly expressed in units of siemens per meter.

The passage of a direct current between metallic electrodes immersed in an ionized solution.

In metals, the electric charges are carried by the electrons of inappreciable mass.

In solutions, the electric charges are carried by electrolytic ions, each having a mass several thousand times as great as the electron.

The positive ions move to the cathode (negative electrode) and the negative ions to the anode (positive electrode).

The movement of charges within a semiconductor due to the displacement of ions within the crystal lattice.

An external source of energy is required to maintain this movement.

A form of nerve impulse conduction in which the impulse jumps from one Ranvier's node (gap) to the next, rather than traveling the entire length of the nerve fiber: Saltatory conduction (from the Latin saltare, "to hop" or "to leap") is the transmission of a nerve impulse from node to node (collection of tissue) of a nerve fiber, rather than along the membrane (thin layer of tissue) which is faster than along unmyelinated fibers.