Twopence is British money: two pennies, an amount rather than a coin you hold. The spelling is what makes it hard — it looks like 'two pence' but the usual British pronunciation is TUP-pence, which is why the dictionary sends you to 'tuppence'. That spelling is simply someone writing down how the word actually sounds. It is a small, old-fashioned word. Two pence today buys nothing, so it survives mostly in fixed phrases where the point is that the amount is tiny: if something is 'not worth twopence', it is worthless; 'to put in your twopence worth' (Americans say 'two cents' worth') means to give your opinion when nobody asked, said with a smile about yourself. You will also meet it in older books and in Mary Poppins, where 'tuppence' feeds the birds. In shops today people say 'two p' — spelled 2p — for the actual coin: 'That'll be forty-two p.' So: 'twopence/tuppence' for the old word and the set phrases, '2p' for the modern coin. One warning about the older books: before 1971 Britain had a different money system, and 'twopence' there was a different, larger amount than today's 2p.

（英國）兩便士。發音是 TUP-pence，所以也寫成 tuppence。現在講實際硬幣多說 2p；twopence 多留在「不值兩便士」這種老式說法裡。