Sentence:  A "partially ordered set" \langle A,\varrho\rangle consists of a nonvoid set A and a <WSD>binary relation</WSD> \varrho on A, such that \varrho satisfies properties (P1)-(P3). 
Meaning of the word marked with <WSD> tags:  A subset of the Cartesian product "A"×"A" (the set of ordered pairs ("a", "b") of elements of "A").