Kickplate: The metal plate that connects the doorknob to the door itself. Usually smudgy with fingerprints and punctured by a keyhole.
Pillion: The "backseat" on a motorcycle or saddle. Also known as the bitch seat.
Ear & Chin: Parts of the letter g. The ear is the little bit that sticks out on the top of a lowercase g, and the chin is the part that forms the little interior table of a capital G.
Gorget: On a bird, the gorget is the front of the neck, where a turtleneck dickie might be worn. Male hummingbirds have bright ones, many pigeons and doves, ringed. In the case of knight's armor, its the same idea: picture a shiny dickie--that's the gorget.
Vamp: A portion of the upper in a shoe. The vamp is the band that runs through laces (if there are any) and holds the arch of the foot to the footbed. In saddle shoes, the vamp is often a different color than the rest of the shoe.
Key ward: This is the part of a key made up of grooves and shapes cut so as to allow access to the lock. Old keys had elaborate wards with cut out designs and shapes. Note: the "bit" is the part of key that the ward is cut into.
Bridge (vs Pickups): On a guitar, the bridge is where all of the strings attach to the body (not the neck) of the guitar. The bridge is a terminus. The pickups, found on electric guitars and a few acoustics just under the strings and before the bridge, "pick up" the vibrations of the strings and turn them into electrical signals that can be amplified and transmitted.
Enallage: A deliberate misuse of grammar, to characterize a speaker (or create a slogan): "I eated it" or "We was robbed."
Your free-write assignment is to pick one of these things and write about it.