1. An olefinic hydrocarbon recovered from refinery processes or petrochemical processes.

Ethylene is used as a petrochemical feedstock for numerous chemical applications and the production of consumer goods.

2. A gaseous hydrocarbon, produced in varying amounts by many plants, that functions as a plant hormone.

Ethylene has wide-ranging effects on plant growth and development, but it is known particularly to stimulate senescence (organic process of growing older) and fruit ripening.