The term "40th" refers to the ordinal number that indicates the position of something in a sequence, specifically the one that comes after the 39th and before the 41st. It is commonly used to denote anniversaries, milestones, or rankings, such as a 40th wedding anniversary or the 40th place in a competition. In various contexts, the 40th can signify significant events or achievements. For example, the 40th President of the United States was Ronald Reagan, who served from 1981 to 1989. Additionally, many cultures celebrate the 40th year as a notable milestone, often associated with wisdom and maturity.