'Chicken'

I think it meant the same thing it's always meant which is scared, and then you have how his mother seems to order his father around, she's the big rooster and he's the timid little chicken, always afraid to speak up or do anything to put her in her place and establish himself as the man of the house. That's what bothered Jim the most because he was growing up, he wanted to know what it took to become a man, he needed his father to tell him that, and his father couldn't, it seems he doesn't know himself what it means. Instead he hides behind shadows of 'logic' and 'in 10 years this will all be over', no direct answers which his son needs.

I would agree with Nova. But i would imagine it would have to do with the culture back than. I can imagine being a teen at that time (50's?) was all about being a man, strong, masculine, border line macho. And it's even "worse" for Jim with his whole situation of moving, new school and stuff. So it would probably be a personal thing for him or a society thing to be taken in so much offense.

Chicken=classy way of saying Pussy

And it wasn't just back in the 50's, even in Back to The Future Marty gets fuming mad when he's called a chicken and in the 90's it was still a huge insult except it moved to being insulting mainly just among kids. Jim just doesn't like being called that because he sees his dad as one and doesn't want to be like him

When people claim that this movie is not dated, I usually remind them that this was the insult that made Jim decide to risk his life. If someone called me a chicken in high school I would look at them dumbfounded, like "are we 7?"

Still a great movie though.