  High entropy oxides are emerging as an exciting new avenue to design highly
tailored functional behaviors that have no traditional counterparts. Study and
application of these materials are bringing together scientists and engineers
from physics, chemistry, and materials science. The diversity of each of these
disciplines comes with perspectives and jargon that may be confusing to those
outside of the individual fields, which can result in miscommunication of
important aspects of research. In this perspective, we provide examples of
research and characterization taken from these different fields to provide a
framework for classifying the differences between compositionally complex
oxides, high entropy oxides, and entropy stabilized oxides, which is intended
to bring a common language to this emerging area. We highlight the critical
importance of understanding a materials crystallinity, composition, and mixing
length scales in determining its true definition.
