the.com/screen door

means A door with a mesh panel that lets air circulate while keeping flying insects out, often paired with a solid main door.

from Straightforward compound: 'screen' in the sense of a protective mesh barrier (from Old French 'escren,' a shield against heat or light) plus 'door.' Wire-mesh screening became cheap and widely available in the 1800s, and the screen door followed quickly after as houses sought summer airflow without the moth and mosquito tax — a humble, functional name for a humble, functional invention.