jī chǔ
base
foundation
basis
underlying
CL:個|个[ge4]
jǐ chū
to squeeze out
to extrude
to drain
to find the time
to burst out
Táng chū Sì Dà jiā
Four Great Poets of early Tang
refers to Yu Shi'nan 虞世南[Yu2 Shi4 nan2], Ouyang Xun 陽歐詢|欧阳询[Ou1 yang2 Xun2], Chu Suiliang 楮遂良[Chu3 Sui4 liang2] and Xue Ji 薛稷[Xue1 Ji4]
jí chǔ
thorny problem
troublesome affair