This paper explores the relationship between conceptualization and metonymy within the framework of cognitive linguistics. Conceptualization refers to the mental process through which humans structure and interpret experiences, while metonymy operates as a cognitive mechanism that allows one conceptual entity to stand for another within the same domain. The paper discusses how metonymy differs from metaphor, yet interacts with it in shaping meaning. By reviewing theoretical perspectives from Lakoff, Johnson, Langacker, and Kövecses, the study demonstrates that metonymy is not merely a linguistic phenomenon but a conceptual tool deeply embedded in human cognition. Several linguistic examples from English illustrate how metonymy functions in discourse to facilitate understanding and mental economy. The study concludes that metonymy plays a central role in conceptual organization, influencing not only language but also thought and cultural representation.