Shoplifting is the crime of stealing things from shops, for example by hiding them in a bag or under your clothes. It names the act as a thing: “Shoplifting is a crime.” Shops, police, and news use it.

Shoplifting is the crime of stealing things from shops是在商店偷東西的犯罪行為, for example by hiding them in a bag or under your clothes比如把東西藏在包包裡或衣服底下。It names the act as a thing是把這個行為當成一個名詞來說: 'Shoplifting is a crime.'「Shoplifting 是一種犯罪。」Shops, police, and news use it商店、警察和新聞都會用這個字。

You can also meet it as the -ing form of the verb (she was shoplifting), but as a headword it is the crime.

You can also meet it as the -ing form of the verb你也會看到它當成動詞的 -ing 形式 (she was shoplifting)（例如 she was shoplifting，她當時正在行竊）, but as a headword it is the crime但作為詞條，它指的是這個罪行本身。

Though actually, this noun is older than the verb shoplift: people were talking about shoplifting around 1690, and only later did English make the verb by cutting it from shoplifter. So it looks like shoplift + -ing, and that is a fair way to see the pieces, but history ran the other way round.

Though actually不過話說回來, this noun is older than the verb shoplift這個名詞其實比動詞 shoplift 更早出現: people were talking about shoplifting around 1690大約1690年人們就在用 shoplifting 這個字了, and only later did English make the verb by cutting it from shoplifter後來英文才從 shoplifter（竊賊）這個字裡切出動詞。So it looks like shoplift + -ing所以它看起來像是 shoplift 加上 -ing, and that is a fair way to see the pieces這樣拆解也不算錯, but history ran the other way round但實際的歷史演變方向剛好相反。