Gland (noun)

1. A group of cells that produces and secretes a substance, such as hormones, enzymes, or milk, for use in the body or for elimination.
2. An organ in the body that produces and secretes substances such as hormones, enzymes, or milk.
3. A group of cells that produces and releases a substance, such as hormones or enzymes.

Origin:

From middle english "glande", from old french "glande", from latin "glandis", from greek "glándis" meaning "acorn".

Examples:

1. The thyroid gland is responsible for producing hormones that regulate the metabolism.
2. The salivary glands produce saliva to help digest food.
3. The lymph glands help the body fight off infections.
4. The sweat glands release sweat to cool the body.
5. The pineal gland produces melatonin, which regulates the sleep-wake cycle.