The phrase "extinguished waterfall" refers to a waterfall that has dried up or is no longer flowing. Some synonyms for this phrase include "dried-up waterfall," "dead waterfall," "silent waterfall," and "vanished waterfall." Other possible synonyms might include "inactive waterfall," "depleted waterfall," "desolate waterfall," or "lifeless waterfall." Regardless of the synonym used, the overall meaning remains the same - a waterfall that once flowed with power and beauty has now been reduced to a shadow of its former self, reminding us of the fragility of nature and the importance of preserving our natural resources.