
Dustin C. answered 07/31/19
Experienced, Patient Teacher Specializing Academic Writing and Math
You are exactly right! The "cat's evening wear" is another way of saying "the cat's pajamas," which is a well-known idiom for something that is the absolute best or coolest. It is a somewhat dated phrase, but it seems to be making a comeback in recent years.
Another idiom that is similar in meaning is "the bee's knees." I have no idea where is came from :)
Hope this helps!
Take care.
Dustin