cell
Noun

smallest working part of a living organism.

digestive system
Noun

series of organs and glands responsible for the ingestion, digestion, and absorption of food. Also called the alimentary canal.

intestine
Noun

tubular system in the human digestive system, which regulates elimination of waste products from the body.

nervous system
Noun

cells, organs, and tissues including the brain and spine that respond to internal and external stimuli.

organ
Noun

musical instrument made of pipes that release different sounds when a keyboard forces air through them.

tissue
Noun

cells that form a specific function in a living organism.