HOSR meaning in General ?

The Thomas Eakins Head of the Schuylkill Regatta (also known as the HOSR or the HOS) is a rowing race held annually during the last weekend in October on the Schuylkill River in Philadelphia, Pennsylvania. The HOSR is the final race in the Fall Fury series, which includes the Head of the Ohio and the Head of the Connecticut. Along with the Head of the Charles and the Head of the Connecticut, the HOSR is considered one of the three “fall classics.” The HOSR is one of the marquee races in the Philadelphia Classic Regatta Series, which also includes the Stotesbury Cup Regatta, the Philadelphia Scholastic Rowing Championship, the Schuylkill Navy Regatta, and the Independence Day Regatta.

Regattas such as the Head of the Charles in Boston and the Head of the Schuylkill in Philadelphia are to the rowing world what the New York Marathon and the Boston Marathon are to running.