WordWeb Online

1. Containing or using responses; alternating
   "responsive reading";
   - antiphonal
    
2. Readily reacting or replying to people or events or stimuli; showing emotion
   "children are often the quickest and most responsive members of the audience";
   - forthcoming
    
3. Reacting to a stimulus
   "the skin of old persons is less responsive than that of younger persons";
   - reactive

See also: answering, respondent, sensitive

Antonym: unresponsive