  The field of Materials Science is concerned with, e.g., properties and
performance of materials. An important class of materials are crystalline
materials that usually contain ``dislocations'' -- a line-like defect type.
Dislocation decisively determine many important materials properties. Over the
past decades, significant effort was put into understanding dislocation
behavior across different length scales both with experimental characterization
techniques as well as with simulations. However, for describing such
dislocation structures there is still a lack of a common standard to represent
and to connect dislocation domain knowledge across different but related
communities. An ontology offers a common foundation to enable knowledge
representation and data interoperability, which are important components to
establish a ``digital twin''. This paper outlines the first steps towards the
design of an ontology in the dislocation domain and shows a connection with the
already existing ontologies in the materials science and engineering domain.
