Do you say "what is onion"?

Onion here refers to the vegetable. Should any article or plural form be used here?


2 Answers 2


Many fruit and vegetables can be countable in the garden or supermarket, and uncountable as an ingredient in food. If someone says "I picked an onion", you can ask "What's an onion?". If someone says "I bought onions at the supermarket", you can ask "What are onions?". If someone says "Do you want onion in your salad?", you can ask "What is onion?".


To ask about the vegetable, you will need an indefinite article here:

  • What's an onion?
  • What are onions?

Both sentences mean just about the same thing, though the second one is probably more idiomatic. In these sentences, you're asking about an the concept of the onion. Without the article you would be asking a different question:

If you say "What is 'onion'?", you're asking about the meaning of the word, not about and explanation of the vegetable. Though the answer to this question may be similar to the possible answers to the other questions, it does not mean exactly the same. You're here asking to explain the meaning of a word.

Should you want to learn more about articles (a/an, the, zero article), you can read up on them here.

  • 2
    Although phrases such as "What is 'onion'?" may be technically correct, verbally they sound the same as "What is onion?" which incorrect and associated with poor English skills. Native speakers will usually avoid this by being more explicit, as in "What does the word 'onion' mean?" Jun 8, 2015 at 23:04
  • 1
    I don't know. As a native English speaker, I would understand 'onion' in a sentence to mean some measured amount, or perhaps asking what onion is, if you're a naive cook looking at a recipe. Because onions come in different sizes, "an onion" could give you too much or too little, where "a cup of onion" is a more precise measurement.
    – jamesqf
    Jun 9, 2015 at 0:27

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