Sentence:  The reading public , the theatergoing public , the skindiving public , the horse-playing public - all these and others fill substantial roles in U. S. life , but none <WSD>is</WSD> so varied , vast and vigilant as the eating public . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)