In hyperbolic geometry, a triangle whose vertices are all ideal; i.e. points at infinity, rather than real.

(physics) the equation of state of an ideal gas

(sociology) Behaviour that is characterized by both the desire and the ability to progress towards an ideal by choosing a new goal when a previous one has been met or the effort to meet it has failed.

(algebra, ring theory) A commutative ring in which every ideal is a principal ideal.

(algebra) An integral domain in which every ideal is a principal ideal.

(algebra) A subring which is both a left ideal and a right ideal. Commonly referred to simply as an ideal, but referred to as two-sided ideal for emphasis.

plural of principal ideal domain

plural of principal ideal ring

(philosophy) A school of philosophy first proposed by Immanuel Kant. It can be juxtaposed with transcendental realism in that it views things in terms of how they appear to the actor rather than how they actually are.

plural of prime ideal