a system of supports beneath a wall or the like.

Often, underpinnings. a foundation or basis

to uncover the emotional underpinnings of an illness.

underpinnings, Informal .

underwear, esp. women's underwear.

the legs.

noun

brace , buttress , crutch , prop , shore , stay , basis , bed , bottom , foot , footing , foundation , fundament , ground , groundwork , seat , substratum , base , substructure , support