The Spanish u is a pure vowel sound formed by rounding the mouth, much like the pronunciation of the vowel sound of "suit" and "moon." It is a single sound; it should never be pronounced like the "u" in "cute" or like the "u" in "bus."
In the combinations ua, ue, ui and uo, the u typically forms a diphthong and is pronounced much like the "u" in "quest" and "quiz."
- When it follows the q, the u is silent. Thus it is not pronounced in words such as que (that, what) and químico (chemical).
- It is also silent in the combinations gue and gui. Thus the u is not pronounced in words such as pague (a subjunctive form of pagar) and guisante (worm). If it is necessary to pronounce the u in such a combination, a diersesis or umlaut (a pair of dots) is placed over the u. Such words are fairly uncommon; among them is pingüino (penguin).