1. Not responding to some influence or stimulus 
2. Aloof or indifferent
   "was unresponsive to her passionate advances" 
3. Not susceptible to suggestion or influence

See also: cool, insensitive, insusceptible, refractory, unresponsiveness, unsusceptible

Antonym: responsive

• falderol
• faldstool
• Falkland Islands
• Falkner
• fall
• fall all over
• fall apart
• fall armyworm
• fall asleep
• fall away
• fall behind
• fall by the wayside
• fall cankerworm
• fall dandelion
• fall down
• fall equinox
• fall flat
• fall for
• fall from grace
• fall guy
• fall in
• fall in line
• fall in love
• fall into
• fall into place