The term "particle" is often used to describe elementary particles because it provides a useful conceptual framework for understanding their behavior and interactions. While it is true that elementary particles are fundamentally described by quantum fields, the term "particle" is a convenient way to refer to the discrete units or quanta of those fields.
In quantum field theory, particles are understood as excitations or disturbances in their corresponding fields. These fields permeate all of space and can exhibit wave-like properties. When a field is excited, it manifests as a particle, which can be thought of as a localized concentration of energy and momentum. These particles can have properties such as mass, charge, and spin, and they interact with other particles and fields in specific ways.
The wave-particle duality in quantum mechanics further complicates the notion of particles. Elementary particles can exhibit both particle-like and wave-like behavior, depending on the experimental context. They can be described by wavefunctions that exhibit interference and superposition, but they also exhibit particle-like properties when interacting with detectors or other particles.
Despite the fact that elementary particles are fundamentally described by quantum fields, referring to them as particles is a useful shorthand that allows us to understand and describe their behavior in many everyday situations. The term "particle" helps us convey the idea of a localized, discrete entity with specific properties and interactions, even though the underlying reality is more complex and involves fields.