Early 16th century; earliest use found in John Skelton (c1460–1529), poet. From puss (although this is apparently first attested slightly later) + cat.
Definition of puss-cat in US English:
puss-cat
nounˈpʊskat
nursery, informal
A cat.
Origin
Early 16th century; earliest use found in John Skelton (c1460–1529), poet. From puss (although this is apparently first attested slightly later) + cat.