Main Entry: hy·po·lim·ni·on

Pronunciation: \ˌhī-pō-ˈlim-nē-ˌän, -nē-ən\

Function: noun

Inflected Form(s): plural hy·po·lim·nia \-nē-ə\

Etymology: New Latin, from hypo- + Greek limnion, diminutive of limnē lake — more at limnetic

Date: 1910

: the part of a lake below the thermocline made up of water that is stagnant and of essentially uniform temperature except during the period of overturn