noun
sunken kotatsu
A low table set over a recessed floor area, often with a heat source underneath and a quilt to trap warmth. Traditional feature in Japanese homes.
See also: 炬燵
冬は掘りごたつに入ってみかんを食べるのが好きです。
In winter, I like sitting at the sunken kotatsu and eating mandarins.
この旅館の部屋には掘りごたつがあります。
This ryokan room has a sunken kotatsu.
Irregular okurigana usage; 掘 is read ほり without the okurigana り.
炬燵 is the general term for a kotatsu, which can be a movable table with a heater and quilt. 掘りごたつ specifically refers to a built-in, sunken version where the floor is recessed.
Compound of 掘り (hori, 'digging', from 掘る horu) + 炬燵 (kotatsu, 'kotatsu'). The term describes a kotatsu built into a sunken floor area.