a hot water bottle / (Kansai) a tall kettle used to heat sake

a hot water bottle

needed, necessary

need, necessity

cold

cold, chilly / (by extension) poor, poverty-stricken / midwinter, cold season

cold, coldness / midwinter, cold season

cold (ambient temperature, as a winter day is cold) / (figuratively) fearful / (of a joke) terrible; not funny

coldness / chill

alternative spelling of 蕩蕩: spacious, grandiose; level and peaceful; gushing, surging, rushing; gentle; disordered, unconstrained