The cover of my round tupperware (ie, reusable plastic food container) says the following:

enter image description here

Dévisser le couvercle avant d' utiliser au micro-ondes

This brought a number of questions to my mind.


utiliser au micro-ondes

The wordreference page for utiliser doesn't really help me understand what prepositions can follow after "utiliser". (In fact, the example sentences only have "utiliser" followed by "pour" -- never "à"!)

I can certainly guess what "utiliser au micro-ondes" means, especially given that the English is there, too. But I would prefer to learn some grammar / principle underneath this, rather than guessing.

  1. What meaning or "feeling" does "au micro-ondes" give? Is it one of the following?

    • Is it "using at the microwave" (ie, literal word-for-word translation)?
    • Is it "using in-the-manner-of-microwaving"?
    • Is "utiliser à + [noun]" a set expression meaning "using with a/the/some [noun]", and wordreference was incorrect for not having an entry for it?
  2. Why is it "au micro-ondes", instead of some other possibilities?

If I were to translate this into English, I would say "using in a microwave" ("à un micro-ondes") or "using in your microwave" ("à votre micro-ondes") or "using in microwaves" (maybe "à des micro-ondes" or "aux micro-ondes").

I don't think English would say "using in the microwave". Does French use the word "the" in a way that sounds strange in English?

  1. How strange would it be if the lid instead said "d'utiliser dans le micro-ondes" or "d'utiliser dans un micro-ondes"?

  2. The wordreference page for micro-ondes seems to have a different definition for "un micro-ondes" and "une micro-ondes", though I can't understand what the difference is:

enter image description here

Anyways, the male version says: "(four à micro-ondes)", which makes me think, what would "avant d'utiliser à micro-ondes" mean?


I learned that French often requires some kind of object, where English leaves it out:

In English: I'm going!
In French: J'y vais! ("I'm going there!")

In English: I know!
In French: Je le sais! ("I know it!")

I had come to think that French always requires this "fuller" sentence that includes the object. So I'm surprised that it's "utiliser au micro-ondes".

  1. Why does "utiliser" in "utiliser au micro-ondes" not require an object for "utiliser"?
  • 1
    "à" is used a lot for cooking. After "réchauffer" or "cuire" you can use "À la poêle", "à la casserole", "au feu de bois" "au four", "au micro-onde", ... Aug 2, 2018 at 8:52

2 Answers 2


Utiliser does not take an indirect complement, so there is no preposition that is particularly associated with it. The following complement is a complément circonstanciel, not a complément d'objet indirect.

Utiliser normally takes a direct complement. Here, it is implicit: the direct complement is the object that the warning is on. The English version uses the same construction: “microwaving” could be replaced by “using in the microwave”.

The construction au/à l'/à la/aux + noun is used for many kinds of tools:

  • frire à la poêle (fry in a pan), griller au four (roast in the oven), réchauffer au micro-ondes (warm up in the microwave), …
  • couper aux ciseaux (cut with scissors), trancher à la hache (cleave with an axe), …
  • écrire au crayon, write with a pencil), …
  • à la main (“by hand”), “à la machine” (using some kind of machine), …

A literal translation of "in a microwave" would be "?dans un micro-ondes", but it doesn't quite have the right meaning. It implies that the object is placed inside the microwave but not that it's used for cooking. The preposition dans would only be used to refer to the physical location of the object, not for its purpose (“Où est mon déjeuner ? Ah, il est dans le micro-ondes, j'ai oublié de le sortir.” = “Where's my lunch? Oh, it's in the microwave, I forgot to take it out.”).

"À un micro-ondes" didn't have the right meaning either. You can't use the indefinite article here because that would refer to one specific, but not yet specified object (“Y a-t-il un micro-ondes dans votre cuisine ?” = “Is there a microwave in your kitchen?”).

Articles and preposition vary a lot between languages and you can't expect simple translations like "à always corresponds to this preposition" or "if there's a definite article in one language then the other language will also use one.

As for the noun micro-onde itself, it has two meanings, like "microwave" in English. It's a term in physics to designate a type of waves, and it's also a type of oven that uses this kind of waves. The noun onde is feminine, and so is micro-onde in the physics sense since adding a prefix doesn't change the gender. Micro-onde as the kitchen appliance is masculine because it's short for un four à micro-ondes.

  • 1
    aha! Especially instructive was your example especially of "à + definite article + tool" as a construction that often suggests purpose or manner, in contrast to what "dans un micro-ondes" which only suggests location instead of manner. Could "à un micro-ondes" work in other contexts? (-"There are four microwaves here. What should I do?" -"Just put the coffee in a microwave, okay? I'm busy", maybe uses "mettre à un micro-ondes"?).
    – silph
    Aug 2, 2018 at 8:29
  • 1
    @silph No, you can't say “mettre à un micro-ondes”. The idiomatic phrasing would be “Mets-le au micro-ondes”, or if you really wanted to say “one of them”, you'd say “Mets-le au micro-ondes, n'importe lequel”. Aug 2, 2018 at 22:07

It's not really a matter of what to put after "utiliser" and more about what to use before "micro-ondes"

Examples (explained later) :

"Utiliser à des fins scientifiques" = "Use for scientific means"

"Utiliser avec des gants" = "Use with gloves / while wearing gloves"

"Mettre au micro onde" = "Put in the microwave"

"Mettre à la poubelle" = "Put in the bin"


  1. "au micro-ondes" gives a very natural and correct feeling, it's most likely what would be used by native French speakers to say it , so the translation is perfect as it is.

  2. On the other hand, you would never ever say "utiliser à un micro-ondes". It would sound very unnatural and just wrong. "Utiliser à..." would rather be used with a condition : "utiliser à une température de XXX / utiliser à la place d'un four" = "use at a temperature of XXX / use instead of an oven".

Or even "at a certain place" : "utiliser à la plage / utiliser à New York" = "use at the beach / NY"

but never "utiliser à [an object]"

  1. "utiliser dans le micro-ondes" would be understandable but would still give a feeling of foreign translation somehow, it sounds a bit unnatural but really not that much. It's just a bit heavy/redundant sounding somehow. "Utiliser dans un micro-ondes" would feel a bit better but still not natural... As I said earlier "utiliser au micro-ondes" was already perfect, anything else would sound less natural.

  2. French nouns are gendered ("une chaise, un tabouret" = "a chair, a stool") and in some cases (like "micro-ondes") the same word exists for both genders but with a different meaning. Here it's either male and an object used to heat food up, or female and is a wave of short length. There is no real equivalent to that in English (as there is no equivalent to the a/an difference in French).

(again, "utiliser à un micro-ondes" doesn't really mean anything, it wouldn't be used in French and would be considered a grammar mistake)


French often requires some kind of object

It's not always true indeed... you could say "je sais !" , rather, "je le sais" can feel very redundant.

In french grammar, there is a notion of "direct object" and "indirect object" that will complement the subject+verb and they can often be dropped from the sentence in shortened, more idiomatic forms.

In "utiliser au micro-ondes", "au" is a sort of shortened "dans le" (which, again, would not sound very good in French), so it already is the "object" and a "fuller" sentence would not sound as smooth and natural.

  • 2
    On the gender of micro-ondes : this word is masculine when it refers to an oven because it is an ellipsis for four à micro-ondes, where four is masculine. That also explains why it is (most of the times) spelt with a plural "s" to ondes, even in the singular. Same phenomenon as eg un deux-roues for un véhicule à deux roues.
    – Greg
    Aug 2, 2018 at 7:17
  • 0/1. As a French learner who only knows English, understanding what "à" means has been a constant challenge. Websites and grammar books give ideas, but still not enough for me to understand it. Your examples where à = "in" ("Mettre à micro-onde") or "for" ("Utiliser à des fins scientifiques") are surprising (and therefore helpful to see). This is what I was trying to ask with question 1: how might I translate "Utiliser au micro-onde" to eventually arrive at the meaning of "in the microwave". Guesses I listed are from the linked website.
    – silph
    Aug 2, 2018 at 7:23
  • 2. So all of these would sound very strange in French: "à un micro-ondes", "aux micro-ondes", "à des micro-onde", "à votre micro-onde"? Should I think of "au micro-onde" more as a kind of short-form of "dans le", and less like "à + definite article"?
    – silph
    Aug 2, 2018 at 7:25
  • 4. Actually, I was asking if "utiliser à micro-onde" makes any sense, and not "utiliser à un micro-onde". P.S. Thank you for your answer -- I comment not to criticize, but to ask for further clarification!
    – silph
    Aug 2, 2018 at 7:26
  • 2
    @silph 2. yes, all these forms are incorrect. You can indeed think of "au" as an equivalent of "dans le" since it marks place. But "au" is terser and more idiomatic in that case. Aug 2, 2018 at 7:37

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