Mibchar (H4309) comes from the root bachar (to choose, elect). It means the cream of the crop β the finest, most excellent specimens. In Genesis it describes the choicest sepulchers; in Numbers, the elite warriors. It conveys absolute excellence, not merely preference but the very best available.
The theological significance flows from the root bachar β God's election. When God calls Israel His chosen people, He is saying they are His mibchar, not because of their inherent superiority, but because of His sovereign grace. The same word used for the finest warriors is used for what God selects for Himself β reminding us that divine election involves both grace and purpose.