Other forms: floorboards
A floorboard is one of the long planks that make up a wooden floor. Nailed down, and at least one of them creaks.
The creak is caused by boards rubbing against each other or against a nail, and it is the reason nobody has ever crept downstairs successfully in an old house. Lifting one is how you reach pipes and cables, and how characters in fiction find things. The word is one word. Putting your foot to the floorboards means accelerating hard, from the floor of a car.
1nounfloorboardOne of the long boards forming a wooden floor.
“A loose floorboard gave him away.”
From floor + board.
Etymology from Wiktionary, CC BY-SA