Chicken

Chickens were a species of bird. Chicken was often used an insult against an individual's bravery.

Bird
The Kaarks resembled humanoid chickens. (DWA: The Playthings of Fo)

The Third Doctor and Jo Grant found a number of chickens in the cargo hold of the SS Bernice. The chickens were destined for Singapore. (DW: Carnival of Monsters)

In 1626, Sir Francis Bacon died of pneumonia, contracted after trying to stuff snow up a chicken. The Doctor claimed to have been present during the former event. (PDA: Heart of TARDIS)

Professor Fyodor Nikolai Kerensky experimented with chickens. He accelerated time, ageing the chicken from an egg, to death. The Fourth Doctor reversed the polarity, regressing the chicken back into egg form. (DW: City of Death)

The Doctor compared the taste of Sneg stew to that of chicken curry. (PDA: Island of Death)

Chiggocks were genetically engineered food animals created by splicing the genes of chickens and pigs. They resembled large headless turkeys. (EDA: To the Slaughter)

The Dong tao chicken was worth four points in the I-Spyder Book of Earth Creatures. (NSA: The Last Dodo)

After being retconned, Harries & Harries went back to serving chickens, amongst other animals. (TW: Meat)

The Chicken of the Apocalypse was the key deity of one of the many religions of the Jaftee. The religion began after one of the Jaftee heard a chicken state that the end of the world was coming. (NSA: Shining Darkness)

Chicken eggs were frequently eaten on Earth. Sarah Jane Smith failed to make scrambled eggs on several occasions. (SJA: The Nightmare Man)

Term
Machine Head played a game of "chicken" with the Raider Leader, tempting the Leader to fly straight into the local sun. (DWM: The Free-Fall Warriors)

In 1941, the Ninth Doctor told Jamie that there was "nobody here but us chickens". (DW: The Empty Child)

Starkey accused Darius Pike of being "chicken". (K9TV: Liberation)