伺

伺隙

sì xì

to wait for the opportunity

难伺候

nán cì hou

(coll.) hard to please; high-maintenance

伺候

cì hou

to serve; to wait upon

伺服

sì fú

servo (small electric motor)

伺服器

sì fú qì

server (computer) (Tw)

伺机

sì jī

to wait for an opportunity

窥伺

kuī sì

to spy upon

观衅伺隙

guān xìn sì xì

lit. to look for holes, and observe gaps (idiom)