(mathematics, algebra) Any finite or infinite series of the form a_0+a_1x+a_2x²…=∑ᵢa_ixⁱ, where the aᵢ are numbers, but it is understood that no value is assigned to x.

(mathematics) A formula which when given a set of n points (x_i,y_i), gives back the unique polynomial of degree (at most) n − 1 in one variable which describes a function passing through those points. The formula is a sum of products, like so: ∑ᵢⁿy_i∏_(j ne i)x-x_j/x_i-x_j. When x=x_i then all terms in the sum other than the iᵗʰ contain a factor x-x_i in the numerator, which becomes equal to zero, thus all terms in the sum other than the iᵗʰ vanish, and the iᵗʰ term has factors x_i-x_j both in the numerator and denominator, which simplify to yield 1, thus the polynomial should return y_i as the function of x_i for any i in the set 1,...,n.

(American football) An offensive formation in which three running backs line up in a row about five yards behind the quarterback, forming a shape like the letter T.

(physics) An equation used to calculate the flow velocity of a fluid in an open-channel system, relating Chezy's coefficient to variables such as radius, roughness, and discharge.

(religion, Christianity) The phrase "in the name of the Father, and of the Son, and of the Holy Spirit", or words to that form and effect, referring to the three persons of the Christian Trinity.

Alternative letter-case form of trinitarian formula

(graph theory) A formula for the number of spanning trees of a complete graph of n vertices: nⁿ⁻².

(mathematics) A mathematical formula relating the vertices, edges and faces of a polyhedron: V-E+F=2

(mathematics) A formula connecting a finite sum of products to a finite continued fraction: a_0+a_0a_1+a_0a_1a_2+⋯+a_0a_1a_2⋯a_n= cfrac a_0 1- cfrac a_1 1+a_1- cfrac a_2 1+a_2- cfrac ddotsddots cfrac a_n-1 1+a_n-1- cfrac a_n 1+a_n,.

An outcrop of rock that forms a distinctive shape.