Baka
The word baka (馬鹿, also 莫迦) is a Japanese word that means idiot, fool or silly (depending on context). It is also used in the English language, especially among fans of anime (and subcultures in close contact) for the same meaning.
The Chinese characters 馬鹿 for baka literally means "horse-deer". The word may come from a story mentioned in Records of the Grand Historian, a 91AD work from China, written by Sima Qian. The story is about how Zhao Gao, who conspired a coup d'etat, tested his servants' loyalty. He referred to his deer offering to Emperor Ying Huhai as a horse. Some followed suit and colled it a horse, while others called it a deer. Zhao Gao called a hit on those who disagreed with him.
A related idiom is Shika o sashite uma to nasu (point at a deer and call it a horse) which comes from the same story. It means to push one's agendas using one's authority, despite having contradictions; also, to make fun of others.
Another theory states that the word baka was first used by Buddhist monks, and the word originated from a Sanskrit word moha. This theory states that the Chinese characters were merely a transcription.
When used as an adjective in Japanese, baka (na) can mean "absurd" or "crazy", not necessarily "idiotic".
During World War II, United States servicemen gave the name "Baka" to the Ohka piloted flying bombs being flown on kamikaze missions against the United States Navy.
Baka is also a tribe of Pygmies.