On a chemical point of vue, many chemicals can be called "something-phosphoramid".
Phosphoramid alone is theoritically a well defined chemical which is different of hexamethylphosphoramid. This latter is phosphramid where 6 hydrogens are substituted for methyl groups (CH3). Is only five where substituted it would be called pentamethylphophoramid. Not only methyl groups can come in, any other radical is theoritically possible. We could have for example
ethyl-penthyl-pentamethylphosphoramid.

However it is still possible that some commercial chemicals use a simplified name. fro example, Hexamethyl alone does not mean anything on a chemical point of vue.