Final answer:
The Greek word for appropriateness is associated with 'prepon' and for seizing the opportune moment, the word 'kairos' is used. Kairos signifies the importance of timing in rhetoric and it can significantly influence the success of persuasive communication.
Step-by-step explanation:
The Greek word for appropriateness is often associated with the concept of 'prepon,' which relates to what is fitting or suitable in a given context. In terms of seizing the opportune moment, the Greek word 'kairos' is used to describe the right, critical, or opportune moment for action. The concept of kairos is significant in rhetoric; it suggests that the success of an appeal can be contingent on the timing of its delivery and the awareness of the audience's circumstances and mood.
For example, if a speaker attempts to persuade an audience to take action immediately following a relevant and pressing event, they are more likely to succeed due to the heightened sensitivity to the issue, which is an application of kairos. Conversely, an appeal made at a less appropriate time may not resonate as effectively. The Greeks emphasized the importance of this concept in various aspects of life, including philosophy, where understanding the 'good life' required discernment of the right actions at the right times.