Risible \RIZ-uh-buhl\ , adjective;
1. Capable of laughing; disposed to laugh
2. Exciting or provoking laughter; worthy of laughter; laughable; amusing
3. Relating to, connected with, or used in laughter; as, "risible muscles"
This word, meaning "given to laughter", dates tot he 1550's and comes from Late Latin risibilis ("laughable, able to laugh"). Risibilis derives from Latin risus, the past participle of ridere ("to laugh"). The sense of "capable of exciting laughter, comical" is first attested in 1727.
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Saturday, February 12
Etymologies come from the Oxford English Dictionary and/or Etymonline.com