(grammar) Referring back to thesubject, or having anobject equal to the subject.
(mathematics) Of arelationR on asetS, such thatxRx for allmembersx ofS (that is, the relation holds between any element of the set and itself).
"Equals" is areflexive relation, as it holds for all possible x; "not less" isnon-reflexive because it is true only for some x and y, "unequal" isirreflexive, as it never holds between x and itself.