Problem: What are the most important words?
symbiosis a relationship in which different organisms live in close association with each other
Answer: association, organism, symbiosis

Problem: What are the most important words?
boat on the lake in the evening
Answer: boat, evening, lake

Problem: What are the most important words?
A couple of male boxers with green gloves are fighting in a stadium.
Answer:
boxer, fight, glove