'Soda biscuit' definitions:

Definition of 'soda biscuit'

noun

Very tender biscuit partially leavened with buttermilk and soda [syn: buttermilk biscuit, soda biscuit]

From: GCIDE

Soda biscuit \So"da biscuit\, n. a bicuit leavened with baking soda and with buttermilk or sour milk. [PJC]