Any of a group of isomers in which atoms are linked in the same order but differ in their spatial arrangement. Open English WordNet

In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms, but differ in the three-dimensional orientations of their atoms in space. Wikipedia

Chemical compounds that have same constitution, but differ in the three-dimensional orientations of their atoms in space Wikidata

isomerism due to differences in the spatial arrangement of atoms without any differences in connectivity or bond multiplicity between the isomers Wikidata

Isomeric molecule whose atomic connectivity is the same but whose atomic arrangement in space is different. OmegaWiki

A form of isomerism in which atoms are arranged differently about a chiral centre (or centre of asymmetry). They exhibit optical activity, and in a molecule with a single chiral centre the two isomers (enantiomers) are mirror images of each other whereas in a molecule with multiple chiral centres the isomers (diastereoisomers) are not normally mirror images. Wiktionary

Form or isomerism. Wiktionary (translation)