fens is a form of:

Fen



noun
1.
ទំនាបបឹង, ដីដាំបន្លែ, វាលភក់ល្បាប់, ទីដក់ទឹកវាលទំនាប, រាប
ENGLISH MEANING
noun
1.
Low land overflowed, or covered wholly or partially with water, but producing sedge, coarse grasses, or other aquatic plants; boggy land; moor; marsh.