What is "underkeep"

Underkeep \Un`der*keep"\, v. t. To keep under, or in subjection; to suppress. [Obs.]
--Spenser.

n. 1 An underground reserve. 2 A keep or storage space located beneath the foundation of a structure; cellar. 3 Any storage space or reservoir placed below another object. 4 An underkeeper, guardian, or custodian. vb. 1 (context transitive English) To keep under or in subjection; subdue; suppress. 2 (context transitive English) To keep or maintain inadequately or below standard.