Sentence:  [W]e had just opened after only 10 cliff‐hanging days in Boston . . . [and] were all doing our first show. The only <WSD>cool cat</WSD> among us was the remarkable director, George Abbott, who had been there many times before and looked pleased, proud and relaxed. 
Meaning of the word marked with <WSD> tags:  An individual who is at ease and self-assured; one who is calm and composed in interactions with others.