noun Date: 15th century the material and construction (as a foundation) used for support of a structure, something that serves as a foundation ; basis , support , underwear , a person's legs
UNDERPINNING
Meaning of UNDERPINNING in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012