thumb意思是「以拇指撥弄」，nose意思是「鼻子」，thumb one's nose at somebody意思是「對著某人用拇指撥弄鼻子」，是一一個挑釁的動作，表示對對方的藐視，說明對方根本不是自己的對手，引申為「不屑一顧。
看看老外聊天時怎麼用thumb nose at：
A Cassie is the last one who hasn't checked my plan.
B Well，she thumbs her nose at your plan.
A 凱茜是最後一個還沒看過我計劃的人。
B 嗯，她並不屑你的計劃。
thumb nose at例句精選：
It may also make foreign leaders who are inclined to thumb their nose at the president think twice.
這也會讓那些喜歡對歐巴馬嗤之以鼻的外國領導人三思。
In school, some students thumb their nose at their teacher.
在學校，某些學生不尊重老師。
表示看不起別人或別人做的事情時。
all fingers and thumbs搞砸事情
Stay away from your brother，he's almost all fingers and thumbs.Have mercy.別煩你弟弟了，他已經快將事情搞砸了。行行好吧。
Cut off your nose to spite your face.意氣用事。
The council failed to stop his ridiculous behavior.No one can keep him from cutting off his nose to spite his face.
議會無法阻止他荒謬的行為。沒人能阻止他的衝動行事。