half-century 
noun
1A period of fifty years.This half-century was the formative period for national kingship....
- Over the last half-century, the number of women in the workplace has tripled.
- This kind of teen, the one that wedged itself into the space between childhood and adulthood and became a monster, is a creature of the last half-century.
1.1A score of fifty in a sporting event, especially a batsman’s score of fifty in cricket.In reply, Grange lost three middle order men for ducks, but young opener C R Bilton struck a fluent half-century before retiring hurt....
- His fellow opener, Mark Bentley, of Netherton, completed a half-century before being bowled by Hamed Khan for 58.
- Follifoot then replied with 142-9 with Neil Walker hitting a half-century.