Definition - What does Cotyledons mean?
Cotyledons are the first leaves that appear on a seedling. The word cotyledon comes from the Greek word for cup. They grow as a pair, and some mutated strains can have three cotyledons. The appearance is round in shape, and they eventually fall off the plant as it matures, grows taller and develops new leaves.
MaximumYield explains Cotyledons
In the seed, the cotyledon is the embryo of the plant. It is the first leaves that appear out of the soil when you have seedlings, and they can be very small. As the seedling grows more leaves appear that resemble the cotyledons, and then leaves that look more mature