lubricant

1. N-MASS A lubricant is a substance which you put on the surfaces or parts of something, especially something mechanical, to make the parts move smoothly. (尤指机械用的)润滑剂; 润滑油

Its nozzle was smeared with some kind of lubricant. 它的喷嘴上涂了种润滑油。

...industrial lubricants. ...工业用润滑剂。

2. N-COUNT If you refer to something as a lubricant in a particular situation, you mean that it helps to make things happen without any problems. (比喻有利于事情顺利进行的)润滑剂[usu supp N]

I think humour is a great lubricant for life. 我认为幽默是一种上好的人生润滑剂。