WordNet sense 1 (chemical agent capable of activity):

active agent

WordNet sense 2 (the voice used to indicate that the grammatical subject of the verb is performing the action or causing the happening denoted by the verb):

active voice

WordNet sense 3 (engaged in or ready for military or naval operations):

fighting, combat-ready

WordNet sense 4 (of or intended for or involved in military operations):

operational

WordNet sense 5 (taking part in an activity):

participating

WordNet sense 6 (connected by participation or association or use):

involved

WordNet sense 7 (having existence or being or actuality):

existent, existing

WordNet sense 8 (expressing action rather than a state of being; used of verbs (e.g. `to run') and participial adjectives (e.g. `running' in `running water')):

dynamic

WordNet sense 9 (capable of erupting):

alive

WordNet sense 10 (advancing in severity):

progressive

WordNet sense 11 (in full operation):

going

WordNet sense 12 (crowded with or characterized by much activity):

busy

WordNet sense 13 (full of energetic and noisy activity):

bustling

WordNet sense 14 (very active):

brisk

WordNet sense 15 (characterized by energetic activity):

lively

WordNet sense 16 (moving quickly and lightly):

agile, nimble, quick, spry