Can two profiles be assigned to one user?

Users have access to Salesforce based on the profile they have been allocated. Many users can be allocated to a single profile. Consider the following scenario: the administrator establishes a sales profile. Now the admin must provide numerous members of the sales team access to a single sales profile. But the admin cannot give a user access to more than one profile because sales reps should only have access to the sales profile. So two profiles cannot be assigned to one user.