Also found in: Dictionary, Thesaurus, Medical, Legal, Encyclopedia.
To boost in size or strength. Most of the wrestlers are bulking up for the weigh-in on Thursday. That country seems to be bulking up their military presence in the region.
bulk upor bulk out
1. To increase in size or weight: The weightlifters are exercising in order to bulk out.
2. To cause someone or something to increase in size, weight, or degree: I hope all the food I'm eating doesn't bulk me out too much. All of the new employees have bulked out the company's payroll.