Final answer:
The external circumstances that influence communication are referred to as the rhetorical situation, which includes genre, purpose, stance, context, and culture.
Step-by-step explanation:
In communication, the external circumstances that influence communication are referred to as the rhetorical situation. The rhetorical situation includes the conditions such as genre, purpose, stance, context, and culture. For example, the genre is the mode of communication, the purpose is the reason for communication, the stance is the viewpoint presented, the context is the setting of the communication, and the culture refers to shared commonalities among the audience. These external circumstances shape how communication is conducted and understood.