Orthoexciton is a term used in physics to describe a particular type of exciton that has parallel spins. There are several synonyms for orthoexciton, including triplet exciton, parallel spin exciton, and aligned spin exciton. Triplet exciton refers to the fact that this type of exciton has three possible spin states. This terminology arises from the Pauli exclusion principle, which states that two electrons in an atom cannot have the same set of quantum numbers. Parallel spin exciton and aligned spin exciton both describe the same phenomenon, where the two electron spins in the exciton are parallel to one another. These terms are often used interchangeably with orthoexciton.