What does « Onion » mean in the Quran?

And [recall] when you said, "O Moses, we can never endure one [kind of] food. So call upon your Lord to bring forth for us from the earth its green herbs and its cucumbers and its garlic and its lentils and its onions." [Moses] said, "Would you exchange what is better for what is less? Go into [any] settlement and indeed, you will have what you have asked." And they were covered with humiliation and poverty and returned with anger from Allah [upon them]. That was because they [repeatedly] disbelieved in the signs of Allah and killed the prophets without right. That was because they disobeyed and were [habitually] transgressing.