thumbs-up 为单数名词，词典就是这种形式。例如：
thumbs-up [singular]
: a gesture in which you hold your hand out with your thumb pointed up in order to say yes, to show approval, etc.The coach gave me a/the thumbs-up after I scored the goal.— often used figurativelyOur proposal got a/the thumbs-up. [=our proposal was approved]The movie got a thumbs-up from most critics. [=most critics liked the movie]