1. Not brought about by coercion or force
   - uncoerced, willing 
2. Not resulting from undue effort; not forced
   "a voice with a pleasingly unforced quality"
   - unstrained

See also: effortless, voluntary

• Heliobacter pylori
• heliocentric
• heliocentric parallax
• heliogram
• heliograph
• heliographic
• heliogravure
• heliolatry
• heliometer
• heliopause
• heliophila
• heliopsis
• Helios
• heliosphere
• heliostat
• heliotherapy
• Heliothis
• heliothis moth
• Heliothis zia
• heliotrope
• heliotropic
• heliotropism
• heliotype
• Heliozoa
• heliozoan