(physics, meteorology) The boundary between two different air masses, or a portion thereof, which produces appreciable cloudiness and precipitation and is usually accompanied by significant shifts in wind direction.

Sewage that has been aerated and agitated in order to promote the growth of beneficial microorganisms that break down organic matter.

(chemistry) A very absorbent form of finely powdered carbon; used in purifying gases, and as an antidote for many poisons.

(chemistry) activated carbon

(military) A state in which person in the military performs military duties on a full-time basis, as opposed to reserve, where one only occasionally performs military duties.

The process of attending carefully to what a speaker is saying, involving such techniques as accurately paraphrasing the speaker's remarks.

The real component of the power of an alternating current circuit; the product of the voltage and that part of the current that is in phase with the voltage

A geologic fault which has exhibited seismic activity within a geologically recent time period.

A form of euthanasia wherein death is intentionally brought about, usually by medical intervention to end the euthanasee's suffering.

Essential components of a device, reaction, etc. / A radioactive material