(literally) a black-feathered bird / (archaic) Synonym of 黒鴨 (kurogamo, “common scoter”) / (archaic) a black chicken

Berkshire pig

a clone

rye

rotary dial telephone / (slang) Kim Jong-un

(Internet slang, especially anime and manga fandom) events or things from the past which one wants to whitewash/erase from history (due to it being embarrassing, poorly received, etc.); dark past

a common crane

(sports) croquet

a black lemur

(geometry) a cycloid