A 3-dimensional geometric arrangement of the atoms or molecules or ions composing a crystal WordNet 3.0 & Open English WordNet

In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions, or molecules in a crystalline material. Wikipedia

In geometry and crystallography, a Bravais lattice, named after Auguste Bravais, is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by R = n 1 a 1 + n 2 a 2 + n 3 a 3, {\displaystyle \mathbf {R} =n_{1}\mathbf {a} _{1}+n_{2}\mathbf {a} _{2}+n_{3}\mathbf {a} _{3},} where the ni are any integers, and ai are primitive translation vectors, or primitive vectors, which lie in different directions and span the lattice. Wikipedia

An infinite array of discrete points generated by a set of discrete translation operations R = n 1 a 1 + n 2 a 2 + n 3 a 3 , where ni are any integers and ai are known as the primitive vectors which lie in different directions and span the lattice. Wiktionary

A regular three-dimensional geometric arrangement of atoms, molecules or ions in a crystal. Wiktionary

Geometric arrangement. Wiktionary (translation)

A crystal lattice. Wiktionary