1close; intimate
2to strengthen (ties, cooperation etc)
3closely; intently; carefully
4(math.) to osculate
Examples
gōng yìng供应hé和xū qiú需求zhī jiān之间de的guān xi关系shí fēn十分mì qiè密切。
供应和需求之间的关系十分密切。
There is close relationship between supply and demand.
我们密切地关注这家工厂几个星期了.
We observed this plant closely for a few weeks.
荷兰语与德语关系密切。
Dutch is closely related to German.