I try to infuse vocabulary into almost everything we do. When we take interactive notes, there are specific vocabulary words that are highlighted and discussed. I also ask vocab questions during transition times (see this blog post for more info) and while we are waiting for slower writers to finish writing.
But what I wanted to share with you today is what I do in the hallway. I have a deck of their vocab words that I add to each unit so that by the end of the year, I have a card with a definition on it for every vocabulary term we have for the entire year. During passing periods, I work my way through the deck asking random students for either the definition of a term or the term for a definition for any of the terms we have had throughout the year.
It is very effective. Sometimes students flock to me saying, "Give me a word!" or, "Watch this," to a friend before defining a tough one. I even have a group of students I had last year who come by almost every morning to do it - and they aren't even in my grade anymore!
Oh, and a quick organizing tip! I color the edge of the cards with a different color to keep track of which words go with which unit.