What is the word for beautiful in french language?

beautiful is spelled beau (masc.) : un beau voyage, un beau vélo (a beautiful journey, a beautiful bicycle) - the plural is 'beaux'. A masculine alternative spelling is 'bel' (un bel homme = a handsome man), used for liaison purposes when the second Word begins with a vowel sound.

It is spelled 'belle' in the feminine: une belle femme (a beautiful woman) - the plural is belles.