1. 主持(仪式)；行使(指定的职务)
When someone officiates at a ceremony or formal occasion, they are in charge and perform the official part of it.

2. （在体育比赛、竞赛等中）担任裁判
When someone officiates at a sports match or competition, they are in charge and make sure the players do not break the rules.

1. perform duties attached to a particular office or place or function

e.g. His wife officiated as his private secretary

Synonym: function

2. act in an official capacity in a ceremony or religious ritual, such as a wedding

e.g. Who officiated at your wedding?