(idiom) everything is ready except for one last key requirement; missing the final vital piece needed for success. This phrase comes from the classic novel "Romance of the Three Kingdoms", referring to an army that had all its equipment ready for a fire attack but was only waiting for the wind to blow in the right direction. It is often used as part of the longer phrase 万事俱备，只欠东风 wàn​shì​jù​bèi​zhǐ​qiàn​dōng​fēng.