1. bi/du
Two

2. biped
“bi” (two) + “ped” (foot) = any animal with only two legs. A human being is the most easily identifiable biped although some might say that it's birds.

3. bifocals
“bi” (two) + focal (like focus) = eyeglasses in which each lens has two parts, one for seeing close things, as in reading, and the other for seeing things far away. Many people need bifocals when they get older.

4. bilingual
“bi” (two) + “lingu” (language) + “al” (having the characteristics of) = a person who can speak TWO languages fluently; adjective describing a person who can speak TWO languages fluently. Being bilingual has a positive effect on intellectual growth.

5. duel
a fight, with rules, between TWO people, may be a contest or a debate; historically involved weapons and was watched by witnesses. I challenged him to a duel.

6. bicuspid
a tooth with TWO points on its top surface; premolar teeth. I have a cavity in one of my top bicuspids!

7. bicentennial
“bi” (two) + “cent” (hundred) = the two hundredth anniversary of a significant event; of or relating to a two-hundredth anniversary. The year 1996 marked Tennessee's bicentennial.

8. duet
a piece of music for TWO voices or TWO instruments; the TWO people who sing or play that piece of music. They sang a lovely duet.

9. duplicity
Dishonesty. Deliberate, deceptive, and tricky doubleness in thought, speech, or action (as in making a deal or a date with TWO people and neither one knows you have a plan with the other one). We were lucky not to be taken in by his duplicity

10. biceps
the TWO large muscles in the front of the upper arms. There are many exercises that specifically target the biceps.

11. dialogue
TWO people talking together, especially an open exchange of ideas, as in an effort to understand each other’s views. Also, the parts of a novel, play, TV show or movie that are conversation. One of the ways an author reveals character is through dialogue.