(grammar) A subordinate clause that modifies a noun.

(grammar) the superlative (a degree of comparison) when it is used to express the highest degree of something in relation to something else

(physics) The theories of special relativity and general relativity, two theories in physics developed mainly by Albert Einstein at the beginning of the 20th century from which several important results such as the equivalence of matter and energy and the Einstein field equations are derived.

(set theory, of set A "in" set B) The set containing exactly those elements belonging to B but not to A.

A person who is related to another through a common ancestor, and not merely by marriage or adoption.

plural of blood relative

(uncountable) A method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock. / (countable) An act of so doing.

plural of relative density

plural of relative clause

plural of relative pronoun