O7

O7 has multiple meanings across different domains, and there is no single universal definition. In some contexts it refers to a formal designation, while in others it appears as a casual symbol or a scientific label.

In the United States military, O-7 denotes a pay grade for one-star officers. The corresponding ranks are Brigadier General in the Army, Air Force, and Marine Corps, and Rear Admiral (lower half) in the Navy and Coast Guard. The designation is used for pay and rank classification rather than a separate title, and officers at this level serve as senior leaders and often hold significant command or staff responsibilities.

In online culture, O7 is a popular emoticon representing a salute. The "O" depicts the head, and the "7" resembles a raised arm in a saluting gesture. It is widely used in forums, gaming communities, and social media to convey respect, acknowledgment, or good wishes.

In astronomy, O7 refers to a spectral subtype of O-type stars. These are among the hottest and most massive stars, with surface temperatures typically in the tens of thousands of kelvin, producing intense ultraviolet radiation. O7 stars are blue-white in color, have strong stellar winds, and lead short lifespans relative to cooler stars. They are commonly found in star-forming regions and contribute to the ionization of surrounding gas.