What is a principal applicant? What is a derivative?
A principal applicant is the person who applies for an immigration benefit, such as U visa status.
A derivative is another person (usually a family member) who may also receive lawful status through the principal applicant’s status. Since the family member’s status is "derived" from the principal applicant’s status, the family member is known as a “derivative” under immigration law.* Although U visa derivatives do not have to meet all of the eligibility requirements for principal U visa applicants, they do have to show they are admissible or they have to file a waiver if they are inadmissible.
To read about principal applicants (known as U-1) and derivatives (known as U-2, U-3, U-4, U5) in the context of U visa status, see What family members may be considered derivatives?
Note: Here you can see our series of vlogs (videos) in Spanish, with English subtitles, where we discuss what other people you can include on your U visa petition as derivative family members, among other topics.