Forming the feminine of adjectives ending in -u in French

In French, the adjectives ending in -u have a specific ending in the feminine form.

The feminine form of adjectives ending in -u in French

Look at these adjectives:

Note that adjectives ending in -u (and NOT derived from verbs) become -üe in the written form, but are pronounced in exactly the same way as the masculine form. 

(The diaresis, ü, indicates here that the u is pronounced as a separate vowel, otherwise, for example, aigue would be pronounced rather like 'egg' in English.) 

Note that before the 1990s, the alternative -uë was the accepted spelling, and is still deemed acceptable now.