Common opposites:
1. Courteous - Discourteous, Rude
2. Intentional - Accidental
3. Frequent - Seldom
4. Bold - Meek, Timid
5. Giant - Tiny, Small, Dwarf
6. Knowledge - Ignorance
7. Pupil - Teacher
8. Amateur - Professional
9. Ancestor - Descendant
10. Elementary - Advanced