What is "aerial root"

n. (context botany English) Any adventitious root that grows from a plant stem above ground.

Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan trees, the warm-temperate rainforest rātā ( Metrosideros robusta) and pōhutukawa ( M. excelsa) trees of New Zealand and vines such as Common Ivy ( Hedera helix) and poison ivy (Toxicodendron radicans).