Longman Dictionary of Contemporary English - active

~1 S2 W2 adj 1 »DOING THINGS« always doing things or ready to do things, especially physical activities  (We had an active holiday, sailing, swimming and water skiing. | She may be over 80, but she's still very active!) 2 »IN AN ORGANIZATION« involved in an organization, activity etc and always busy doing things to help it ~ member  (an active member of the local Historical Society) be ~ in (doing) sth  (He's very active in local politics. | She's been active in raising money for the new church buildings.) 3 ~ efforts/discussions etc efforts, attempts etc to do something, solve a problem etc, that are made with continuous energy and determination  (Active efforts are being made to reach a settlement.) 4 »ELECTRICAL SYSTEM« technical operating in the way it is supposed to  (The alarm becomes active when the switch is turned on.) 5 »MILITARY« a) on ~ service a soldier etc who is on active service is fighting in a war b) on ~ duty AmE employed by the army etc, as opposed to being in the reserves (reserve2 (6)) 6 »VOLCANO« likely to explode and pour out fire 7 »GRAMMAR« technical if a verb or sentence is ~, the person or thing doing the action is the subject1 (5). In `The boy kicked the ball', the verb `kick' is ~.  (- compare passive1 (2)) 8 »CHEMICAL« technical producing a reaction in a substance or with another chemical - ~ly adv  (The two sides are actively engaged in discussions.) ~2 n the ~/the ~ voice technical the ~ form of a verb  (- compare passive2)