Definition of “stone” - Learner’s Dictionary

stone

noun uk us /stəʊn/
SUBSTANCE [ U ]

B1 a hard, natural substance that is found in the ground:

a stone wall
ROCK [ C ]

B1 a small rock or piece of rock

JEWEL [ C ]

B1 a hard, valuable substance that is often used in jewellery:

precious stones
WEIGHT [ C ] (plural stone) UK

a unit for measuring weight, equal to 6.35 kilograms or 14 pounds:

I gained two stone when I was pregnant.
SEED [ C ]

the hard seed that is at the centre of some fruits:

a cherry stone
→ See also stepping-stone

(Definition of “stone noun” from the Cambridge Learner's Dictionary © Cambridge University Press)