adversary
The definition for adversary is "One who opposes or resists." Used in a sentence: Franklin hoped to defeat his adversary in the afternoon's tennis match.
avian
The definition for avian is "Relating to birds." Used in a sentence: The old man affectionately referred to pigeons as his "avian friends."
frugal
The definition for frugal is "Thrifty, cheap." Used in a sentence: The frugal shopper only bought items that were on sale.
proximity
The definition for proximity is "Closeness." Used in a sentence: The proximity of Tia's house to school meant that she could walk there in five minutes.
repel
The definition for repel is "To resist, reject." Used in a sentence: The soldiers made a massive charge to repel the invaders.