lowest part; bottom
Refers to the physical or metaphorical lowest section of something, such as the bottom of a page, screen, list, or hierarchy.
Please scroll to the bottom of the screen.
Please sign at the bottom of this document.
Compound of 最 (sai, 'most') + 下部 (kabu, 'lower part'). The reading さいかぶ follows standard on'yomi.