Sentence:  Fight sequences fall into one of three categories: “MAMs” (many against many), “OHMs” (one hits many), and “triple O′s” (one on one). Group fights — MAMs and OHMs — are more difficult to choreograph than <WSD>triple O</WSD>′s, and TV shows that included well-choreographed MAMs and OHMs received higher marks than those devoid of mass attacks. 
Meaning of the word marked with <WSD> tags:  A one-on-one.