amphibious

Amphibious is an adjective describing something that can operate or exist in both land and water. The word derives from Greek amphi- 'both' and bios 'life'. In biology, it refers to organisms that live part of their life in water and part on land; in engineering, to equipment designed for both media.

Biology: The best-known amphibians are frogs, salamanders, and caecilians. Most begin life in water as eggs that hatch into larval forms with gills, then undergo metamorphosis to develop legs and lungs. Amphibians typically have moist, permeable skin for respiration and water balance. Many require damp habitats for reproduction, while others are mostly terrestrial as adults.

Habitat and ecology: Amphibians occur in diverse environments, from ponds and streams to forests and grasslands. They are predators and prey and can indicate environmental health due to sensitivity to moisture, temperature, and pollution. Major threats include habitat loss, pollution, climate change, and fungal diseases.

Beyond biology, the term also describes vehicles, ships, or aircraft designed to operate on both land and water. Amphibious craft enable coastal landings, river crossings, and other dual-environment tasks; examples range from historical DUKW to modern amphibious assault ships.

In summary, amphibious denotes dual-environment capability across biological, engineering, and military contexts, highlighting adaptability to terrestrial and aquatic conditions.