noun. In anatomy, a muscle surrounding an orifice, as that of the mouth or eyelids; a sphincter.

"The muscle that controls eye-smiling is called the orbicularis oculi, and its activation has proved to be a reliable indicator of internal happiness or mirth."

orbicularis ani  orbicularis oris  orbicularis palpebrarum  orbicularis panniculi  

bulbus  dilator  extra-ocular  homo  mercedem