die Zitrone
lemon
A sour, yellow citrus fruit with an oval shape, used for its juice and peel in foods and drinks.
Für den Tee hätte ich gerne eine Scheibe Zitrone.
For the tea, I would like a slice of lemon.

lemon
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lemon
A sour, yellow citrus fruit with an oval shape, used for its juice and peel in foods and drinks.
Für den Tee hätte ich gerne eine Scheibe Zitrone.
For the tea, I would like a slice of lemon.

Whether the fruit or a defective product is meant becomes clear from context. If it is about food, drinks, or cooking, it always means the fruit. If people are talking about a purchased product, especially a car that does not work, the figurative meaning is meant.
Ich presse mir morgens immer den Saft einer Zitrone aus.
I always squeeze the juice of a lemon for myself in the morning.
In connection with the fruit, 'Zitrone' (lemon) is often used in fixed combinations. Typical examples are 'heiße Zitrone' (hot lemon drink), 'der Saft einer Zitrone' (the juice of a lemon), or the question 'mit Zitrone?' (with lemon?), for example with tea or water.
Eine heiße Zitrone mit Honig hilft bei Erkältungen.
A hot lemon drink with honey helps with colds.
Calling a product a 'Zitrone' (lemon) is colloquial. It is mostly used for expensive purchases such as cars or electronics that cause many problems right from the start.
Er hat eine Zitrone gekauft; der Motor war schon nach einer Woche kaputt.
He bought a lemon; the engine was broken after just one week.
cucumber
'die Gurke' and 'die Zitrone' are actually different foods, but colloquially they can also refer to a bad product, especially a car. In this figurative meaning, 'eine Gurke' often means an old, bad, or unreliable vehicle or device. 'Eine Zitrone' especially means a product that constantly has defects and keeps causing problems. Learners may confuse the words because both can be used negatively for things. Practically speaking: 'Gurke' sounds more general and very colloquial, while 'Zitrone' emphasizes many defects after purchase.

Nach der dritten Reparatur wusste Paul, dass sein neues Auto eine Zitrone war.
After the third repair, Paul knew that his new car was a lemon.
Mein alter Laptop ist wirklich eine Gurke und startet nur noch langsam.
My old laptop is a real clunker and now only starts up slowly.