palpable purpura, arthralgia, and weakness: three symptoms that suggest a diagnosis of cryoglobulinemia

(grammar) Grammatical number denoting a quantity of exactly three

The triangle formed by joining the points of intersection of the lines from each vertex of a triangle to its Brocard points.

Synonym of frame harp

plural of triangular harp

(baseball) A fielding play where the fielders deceive the baserunners as to the location of the ball, allowing one of the fielders to attempt to tag a runner out without the runner being aware of it.

(set theory) A method for giving a definition of equivalence classes for equivalence relations on a proper class, relying on the axiom of regularity but not on the axiom of choice.

The three symptoms of Currarino syndrome.

An optical illusion in which a number of spatially separated fragments give the illusory impression of the contours of a triangle.

Any magic trick involving playing cards.