(chemistry) activated carbon

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

(volcanology, geology) A volcano that has erupted in the last 10,000 years, although not necessarily venting lava or gases now.

In set dances with more than one couple dancing, the couple doing the more complicated movement during any given portion of the dance. The role of active couple may pass from one couple to another. In many quadrilles, certain figures will have two active couples at any one time; in long set dances, quite often every other couple or every third couple is the active couple.

The increase in rate of a chemical reaction caused by the presence of a catalyst. / An amount of catalyst, expressed as the increase of the rate of its reaction.

plural of active couple

(chemistry) A transitional structure, in an energetically excited state, that forms between the reactants of a chemical reaction and breaks down to form the products

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.