Solarium and Sun porch

Solarium noun - A room enclosed largely with glass and affording exposure to the sun.

Sun porch is a synonym for solarium. In some cases you can use "Sun porch" instead a noun "Solarium".

Sun porch noun - A room enclosed largely with glass and affording exposure to the sun.

Solarium is a synonym for sun porch. You can use "Solarium" instead a noun phrase "Sun porch".