A tightrope walker or a similar performer on a slack rope.

(slang) An insane asylum.

(physics) Any of the subatomic particles that does not consist of other, smaller particles; the gauge bosons, leptons and quarks.

(calculus) Of a function, another function, the value of which for any value of the independent variable is the instantaneous rate of change of the given function at that value of the independent variable.

Any spider of the family Agelenidae.

(medicine) any of several biochemical blood assays designed to give information on the state of a patient's liver; include total protein, albumin, alanine transaminase, alkaline phosphatase and bilirubin

(physics) any of a set of physical quantities that play a fundamental role in basic theories

(physics) any of the fundamental forces that act between elementary particles; each one is associated with an exchanged particle

(informal) To perform below one's capacities. / (informal) To promise more than one can deliver.

A venomous spider, Atrax robustus, native to the greater Sydney region of eastern Australia.