Only one line can be drawn through a point parallel to another line WordNet 3.0 & Open English WordNet

In geometry, the parallel postulate, also called Euclid's fifth postulate because it is the fifth postulate in Euclid's Elements, is a distinctive axiom in Euclidean geometry. Wikipedia

Axiom in Euclidean geometry Wikidata

An axiom of Euclidean geometry equivalent to the statement that, given a straight line L and a point P not on the line, there exists exactly one straight line parallel to L that passes through P; a variant of this axiom, such that the number of lines parallel to L that pass through P may be zero or more than one. Wiktionary

Axiom of Euclidean geometry. Wiktionary (translation)