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

(chemistry) activated carbon

plural of activated complex

That responds to spoken commands.

plural of activated sludge

Alternative form of reactivate

plural of ultrahazardous activity

(law) An activity that is so dangerous that any person engaging in it will be held strictly liable for harm caused by engaging in the activity, no matter what precautions were taken to prevent harm; common examples include using explosives, radiation, and poisonous chemicals, and handling wild animals.

(grammar, uncountable) the form in which the subject of a verb carries out some action / (grammar, countable) a form in a particular language used to express the active voice

(chemistry, physics) The energy required to initiate a reaction. For example, the flame from the fuse of a firecracker provides a small initial amount of energy, after which the explosive reaction proceeds by itself, releasing a considerably larger quantity of energy. A small push given to a stable but top-heavy object may cause it to fall over; the potential energy released during the fall was present in the system all along but could not be realized as long as the object was upright and balanced.