"Floor" is the horizontal surface inside a building; "ground" is the surface of the earth outdoors.
Noun. The surface you walk on inside a building or room. Also used for levels of a building: "the third floor".
The baby dropped her toy on the floor.
El bebe dejo caer su juguete en el piso.
My office is on the fifth floor.
Mi oficina esta en el quinto piso.
Please sweep the kitchen floor before dinner.
Por favor barre el piso de la cocina antes de cenar.
Noun. The surface of the earth, especially outdoors. Also used for the surface in natural spaces like forests or fields.
The children were sitting on the ground under a tree.
Los ninos estaban sentados en el suelo debajo de un arbol.
After the earthquake, many buildings fell to the ground.
Despues del terremoto, muchos edificios cayeron al suelo.
The leaves covered the ground in the forest.
Las hojas cubrieron el suelo en el bosque.
Common mistake
Common error: saying "I dropped my keys on the ground" when you are inside a kitchen. While not entirely wrong in informal speech, "on the floor" is more natural indoors. Reserve "ground" for open, outdoor spaces. Note: "ground floor" (primer piso) is a fixed compound noun used in British English.
Trick to remember it
Ask: are you inside or outside? Inside a building: "floor". Outside under the sky: "ground". Exception: "ground floor" is a fixed compound (the first level of a building), especially in British English.
Quick rule
Floor = inside a building. Ground = outdoors, on the earth.
Did you know?
In American English, the first level of a building is the "first floor". In British English, the first level is the "ground floor" and the next one up is the "first floor". So when talking to British speakers, "first floor" may mean the second level in American terms.
Exercise 1 · Pick the right one
She slipped and fell on the wet _____ in the bathroom.
Exercise 2 · Pick the right one
After the storm, branches were scattered all over the _____ in the park.
Exercise 3 · Form the word
Floor = inside a building. Ground = outdoors, on the earth.
Common error: saying "I dropped my keys on the ground" when you are inside a kitchen. While not entirely wrong in informal speech, "on the floor" is more natural indoors. Reserve "ground" for open, outdoor spaces. Note: "ground floor" (primer piso) is a fixed compound noun used in British English.
Ask: are you inside or outside? Inside a building: "floor". Outside under the sky: "ground". Exception: "ground floor" is a fixed compound (the first level of a building), especially in British English.
Bryan López
Founder of SpeakUP Academy