CON - To study, especially in order to gain knowledge of.
NOD - To incline the head up and down, as to indicate agreement.
NOR - Used to introduce a further negative statement.
ROD - A straight, round stick, shaft, bar, cane, or staff.
COO - The murmuring sound made by a dove or pigeon.
DON - A university professor, particularly one at Oxford or Cambridge.
CORD - A long, thin, flexible length of twisted yarns (strands) of fiber.
CORN - A cereal plant grown for its grain, specifically the main such plant grown in a given region, such as oats in parts of Scotland and Ireland, wheat or barley in England and Wales, and maize or sweetcorn in the Americas.
DOOR - A portal of entry into a building or room, consisting of a rigid plane movable on a hinge. Doors are frequently made of wood or metal. May have a handle to help open and close, a latch to hold the door closed, and a lock that ensures the door cannot be opened without the key.
ODOR - Any smell, whether fragrant or offensive; scent; perfume.
CONDO - A condominium.
DONOR - One who donates, typically, money.
CROON - To hum or sing softly or in a sentimental manner.
CONDOR - Either of two New World vultures, Vultur gryphus of the Andes or Gymnogyps californianus, a nearly extinct vulture of the mountains of California.
CORDON - A ribbon normally worn diagonally across the chest as a decoration or insignia of rank etc.