29 CFR 1471.995: Principal.

Principal means—

(a) An officer, director, owner, partner, principal investigator, or other person within a participant with management or supervisory responsibilities related to a covered transaction; or

(b) A consultant or other person, whether or not employed by the participant or paid with Federal funds, who—

(1) Is in a position to handle Federal funds;

(2) Is in a position to influence or control the use of those funds; or,

(3) Occupies a technical or professional position capable of substantially influencing the development or outcome of an activity required to perform the covered transaction.