Nissonite is a term used to describe a mineral that has a hexagonal crystal structure. However, there are several synonyms that can be used instead of nissonite. For instance, it can be referred to as Ilmenite, which is a titanium-iron oxide mineral that shares several similar characteristics with nissonite. Another possible synonym is ferrian ilmenite, which is a variety of ilmenite that contains iron. In addition, nissonite can also be referred to as pseudobrookite, which is a type of titanium oxide mineral that has a similar crystal structure as nissonite. Finally, it can also be called titanium magnetite, which is a rare type of magnetite that contains titanium.