lowland
low-land
adjective
Pertaining to or characteristic of a low-lying region of land.
"Lowland areas are often suitable for farming."
noun
An area of land that is low in elevation, typically flat or gently rolling.
"They live in the fertile lowland near the river."
Thesaurus
Synonyms: low-lying, sea-level
Antonyms: highland, highland(a), upland