noun, plural ric·tus, ric·tus·es. 1.the gape of the mouth of a bird.
2.the gaping or opening of the mouth.
Origin:
1750–60; < Latin: wide-open mouth, equivalent to rig-, variant stem of ringī to open the mouth wide + -tus suffix of v. action.
Related forms ric·tal, adjective
sub·ric·tal, adjective