四

四面八方

sì miàn bā fāng

(idiom) all directions; all around

四书

sì shū

Four Books, namely: the Great Learning 大學|大学, the Doctrine of the Mean 中庸, the Analects of Confucius 論語|论语, and Mencius 孟子

四海

sì hǎi

(fig.) the whole world

四处

sì chù

all over the place

一年四季

yī nián sì jì

all year round

四小龙

sì xiǎo lóng

Four Asian Tigers

四舍五入

sì shě wǔ rù

(math.) to round up or down

四声

sì shēng

the four tones of Middle Chinese: level tone 平聲|平声, rising tone 上聲|上声, departing tone 去聲|去声 and entering tone 入聲|入声

四大发明

sì dà fā míng

the four great Chinese inventions: paper, printing, magnetic compass and gunpowder

四国

sì guó

Shikoku (one of the four main islands of Japan)

四大

sì dà

the four elements: earth, water, fire, and wind (Buddhism)

四重奏

sì chóng zòu

quartet (musical ensemble)