Slang?

There are some words that have been used in Chicago but its doesn't appear in my eng-eng dictionary..

1.lavalier
2.veg (it does exist but I don't think thats the real meaning, it said the meaning is vegetable)
3.nerts
4.girder( it does exist in the dictionary but I don't think that was what they try to say in the movie)
5.onyx(same as above)