n.
1.any substance used to slow down neutrons in nuclear reactors
2.in the Presdyterian church, the officer who presides over a synod or general assembly
3.someone who presides over a forum or debate
4.someone who mediates disputes and attempts to avoid violence
Idiom of the Day
have an in with (someone)
to have a way to request a special favor from someone
The woman has an in with her boss and can easily get time off.