Definition: a master of ceremonies or host of an even such as a comedy evening or review show*
Used in a sentence: The MCcompere for the talent show obviously had no talent of his own.
*Ross tells me that, at least in the UK, the two words (MC and compere) have different meanings- though he struggled to explain to me what they were. Apparently, at one point, the MC was a more formal position that remained off stage and organized events whilst the compere was more participatory. He does concede that the two are pretty much interchangeable now. I'm allowing it because I'd never heard the term compere before meeting Ross... so there!