1. ped = foot

2. a creature with two feet
biped (n)
a creature with two feet

3. centipede (n)
a creature with 100 feet

4. something that stands in one’s way; an obstacle.
impediment (n)
something that stands in one’s way; an obstacle.

5. millipede (n)
a creature with 1,000 feet

6. a lever that is moved with one’s foot
pedal (n)
a lever that is moved with one’s foot

7. a person who goes from door to door on foot trying to sell a product
peddler (n)
a person who goes from door to door on foot trying to sell a product

8. a person who walks across the street on foot
pedestrian (n)
a person who walks across the street on foot

9. pedicure (n)
a foot treatment that could include soaking the feet and polishing the toenails

10. a four-footed creature
quadruped (n)
a four-footed creature

11. a three-footed stand often used to balance a camera
tripod (n)
a three-footed stand often used to balance a camera

12. handing down from age to age;
traditional (adj)
handing down from age to age;

13. structure (n)
the framework or arrangement of how a story (narrative) is told verbally or in writing