四

universal brotherhood

April Theses; series of directives issued by Lenin after his return from exile

four-part harmony

Martial arts

tate-shiho-gatame (judo); vertical four-quarter hold

being preoccupied with immediate (superficial) differences without realizing that there are no differences in substance; six of one and half a dozen of another

love-sickness

the 64 hexagrams (of the Book of Changes)

April fool

four-letter word (esp. in English)

sleep four hours and pass, sleep five hours and fail (when cramming for university entrance exams)

May Fourth Movement (anti-imperialist student demonstration in Beijing on May 4, 1919)

Linguistics

yodan verb conjugation; verb conjugation of classical Japanese

four-armed scoop net

Yokkaichi asthma

Medicine

quadriplegia; tetraplegia

carbon-14

Chamisso's lousewort (Pedicularis chamissonis var. japonica)

the four great civilizations of the world (China, Babylon, India, and Egypt; as put forward by Chinese scholar Liang Qichao in 1900)

Four Classic Novels of Chinese literature (Romance of the Three Kingdoms, Journey to the West, Water Margin, and The Plum in the Golden Vase)

Sumo

wrestling in which both wrestlers grasp the other's belt with both hands

Buddhism

four kinds of birth in the six destinies

From Confucius

at age forty, one has no doubts

Mathematics

four-color theorem; four-color map theorem

Anatomy

fourth ventricle; brain structure