Adjective

1. blue

   Le ciel est bleu. - The sky is blue

2. very rare, underdone

Noun

1. The color blue
2. blue cheese

   Le bleu ressemble au roquefort - Blue cheese looks like Roquefort

3. rookie, new recruit, raw recruit

   Ce soldat est un vrai bleu - This soldier is a real rookie

4. bruise

   Il est tombé, et maintenant il a un bleu - He fell over and now he has a bruise

5. a supporter of the Conservative Party