The lower floor of a house, at ground level.
"The smell of fresh coffee drifted up from downstairs where my grandfather was making breakfast."
A floor lower than the current one.
"The smell of fresh coffee drifted upstairs, making me realize my mom must be downstairs already."
living, stepping, or coming down the stairs
"When I heard someone laughing downstairs, I ran to see who was visiting my parents."
This word combines "down," "stair," and the plural suffix "-s." It originally referred to steps leading downward, which evolved into the modern meaning of a lower floor or level.