tending to become more severe or wider in scope(adj.all)
Example: Active tuberculosis.
source: wordnet30
disposed to take action or effectuate change(adj.all)
Example: A director who takes an active interest in corporate operations.
An active antagonism.
He was active in drawing attention to their grievances.
Example: Active duty.
Though past retirement age he is still active in his profession.
source: wordnet30
Having the power or quality of acting; causing change; communicating action or motion; acting; -- opposed to passive, that receives; as, certain active principles; the powers of the mind.(adjective)
source: webster1913
noun (n)
chemical agent capable of activity(noun.substance)
the voice used to indicate that the grammatical subject of the verb is performing the action or causing the happening denoted by the verb(noun.linkdef)
Example: `The boy threw the ball' uses the active voice.