meaning of "cat's pajamas"

[Zishuli]

English Language Tests, Intermediate level

ESL/EFL Test #317 "English Slang Idioms (38)", question 7

"The sirloin at that restaurant is the cat's .........," Hal said to Harry.

(a) paws
(b) nip
(c) bandana
(d) pajamas

English Language Tests, Intermediate level

ESL/EFL Test #317 "English Slang Idioms (38)", answer 7

"The sirloin at that restaurant is the cat's pajamas," Hal said to Harry.

Correct answer: (d) pajamas

Your answer was: correct
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Hi,
I have tried to look up the dictionary but I can't make out the meaning of " cat's pajamas".

Would somebody help me? Thanks.

[Jamie (K)]

If something is "the cat's pajamas", it means that it's really great, the greatest. Sometimes it means that something is in fashion and that everyone is interested in it or wants it.

It's a very old idiom that isn't used very much anymore.