Definition of bottle up

The phrase "bottle up" is an idiomatic expression used to describe the act of suppressing or keeping something inside, often emotional or mental states. The origin of this phrase can be traced back to the medieval era when people started using bottles to store and preserve liquids, as there were no modern-day technologies to do so. In those times, bottles were often made of glass, and they were carefully sealed to prevent any leakage or contamination. To prevent the air from entering the bottles and contaminating the liquids inside, corks were used as stoppers. Since the corks were tight, the bottles were easily associated with holding back or suppressing something. The expression "bottle up" thus originated from this analogy. Just as a bottle is tightly sealed and prevents anything from coming out, people use the phrase to depict the action of keeping emotions or thoughts inside, as if those thoughts and emotions were preserved and bottled up inside us. While the expression's origin is historical, its continued usage today suggests that human experiences of internalizing emotions and thoughts have not changed significantly over time.