A secret society for students at Yale University in New Haven, Connecticut.

Like a skull.

Alternative form of out of one's mind

(pathology) Any of a wide variety of craniofacial and skull base disorders affecting the area of the head and/or neck, from the clavicle to the top of the skull.

plural of skull base disease

(informal, entomology) Formica archboldi, a kind of ant that hunts trap jaw ants and takes their decapitated heads back to its nest.

(law) a common-law rule according to which a defendant is not liable for the plaintiff's conditions or injuries that predate the tort, except to the degree that the tort worsened or hastened that injury or condition

(law) Synonym of eggshell rule

(obsolete, idiomatic, slang) I'm awake; I'm alert; I know what's happening.

(colloquial) Synonym of get it through one's head