Final answer:
A simplified representation of a complex entity or phenomenon in science is known as a model, which helps in visualizing and understanding various aspects of the entity, such as in modern physics with relativity and quantum mechanics.
Step-by-step explanation:
A simplified representation of a complex entity or phenomenon is known as a model. Scientific models help translate the intangible or the extremely complex into human terms that we can visualize, discuss, and hypothesize about. For instance, the electron cloud model of the atom, despite its simplified depiction, allows us to conceptualize where an electron might be located around the nucleus even though it doesn't pinpoint an electron's exact location at any given time. The use of models is crucial in areas like modern physics, where phenomena are understood through the frameworks of relativity and quantum mechanics, which are often represented through theoretical models rather than direct observation.