reciprocity (answer as in reaction)
ethnocentricity, ethnicity
Headache starts and ends with the letters he. Another word is heartache.
One word for a suitor that ends with "u" is "beau."
A word that ends with 'ible' and means that can be eaten is edible.
Another word to describe the most intelligent that ends with -est is 'smartest. ' "She is the smartest girl in the room. "
Sienna could be the word you want.
or
ecru
sentry
Evident
Finalize
owe