Modifies a noun

• anniversary: In May 2006 a group of former DJs came together to celebrate the fortieth anniversary of the launch of Radio England.

• birthday: Notes Janet Downes thinks she has found the secret for a happy marriage: she's marrying herself on her fortieth birthday.

• celebration: See also pictures from Radio Caroline's, Radio London's and Radio Essex's fortieth anniversary celebrations.

• year: The fortieth year of the George Formby Society came to a close with the final group ' thrash ' on Sunday 25th November 2001.

• day: On the fortieth day, Anne came out of her trance to find the world had been replaced by an ocean.

• part: In 1618 only a fortieth part of the people was connected with the Church of Rome.