How do you say dimensions in French — “de long” or “de longueur”?

To state a size, French puts the number first and then an adjective introduced by de: une table de 180 centimètres de long, 80 centimètres de large, 75 centimètres de haut. The adjective never agrees — it stays long, large, haut whatever the noun. The nouns longueur, largeur and hauteur exist too, but for a plain measurement the short adjective form is what people actually say.

The same slot takes other adjectives: deux mètres de profond (deep), trois centimètres d’épais (thick). Ask for the measurement and the sentence changes shape instead: quelle est la longueur ? or, as in this furniture-shop exchange, the very spoken c’est quoi, la longueur ? One more to pocket from the scene: une table extensible, an extendable table — the everyday word for one with a leaf.