1
general::
Phrase(s): weak as a kitten
Go to *weak as a baby and *weak as a kitten
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Feeble and fragile, as in After that bout with flu she was weak as a kitten. This simile has largely replaced weak as a cat, from the early 1800s.
American Heritage Idioms