Grownup and Grown-up

Grownup adjective - (of animals) fully developed.

Grown-up and grownup are semantically related. in developed topic. In some cases you can use "Grown-up" instead the word "Grownup" as an adjective or a noun, when it comes to topics like grown, experienced, fully grown, nubile.

Grown-up adjective - Relating to or typical of adults; displaying proper maturity.

Grownup and grown-up are semantically related. Sometimes you can replace term "Grownup" with "Grown-up", this terms are similar.