12 CFR 161.35: Officer.

The term Officer means the president, any vice-president (but not an assistant vice-president, second vice-president, or other vice president having authority similar to an assistant or second vice-president), the secretary, the treasurer, the comptroller, and any other person performing similar functions with respect to any organization whether incorporated or unincorporated. The term officer also includes the chairman of the board of directors if the chairman is authorized by the charter or by-laws of the organization to participate in its operating management or if the chairman in fact participates in such management.