The Collaborative International Dictionary of English v.0.48:
blue jeans \blue" jeans`\, n. pl.
a tight-fitting trousers made of blue denim or a similar
fabric, designed originally to serve as inexpensive durable
workclothes, and often having metal rivets for reinforcement.
They have become very popular as casual wear for all age
groups, and more expensive and more carefully styled and
tailored versions called designer jeanshave also become
popular among girls and women.
Syn: jeans, Levis. [1913 Webster]