Referring to a perspective or view from the real world, in contrast to a perspective from within the fictional world.

A religion which encourages theological liberalism and an individual search for truth and the adherents of which draw on many different theological sources and have a wide range of beliefs and practices.

A coupling that allows different parts of a machine not in line with each other some freedom of movement at the same time as transmitting rotary motion.

(philosophy, metaphysics) A universe in which all of the actions of matter and energy operate as reactions according to predetermined rules set down by a creator, like the movements of a clock.

plural of clockwork universe

(uncountable) A branch of mathematics dealing with equational classes of algebras, where similar theorems from disparate branches of algebra are unified.

(medicine) A person with blood type O, which lacks antigens and is therefore compatible with all other blood types, allowing them to donate blood to any other person.

(mathematics) The property of there being a unique morphism from an arbitrary object to the universal morphism of a comma category which is from a functor to a fixed object; or, dually, the property of there being a unique morphism from the universal morphism to an arbitrary object of a comma category which is from a fixed object to a functor. (Caveat: the uniqueness is up to isomorphism.)

plural of universal donor

Alternative form of alternate universe