The Hebrew verb adar means to be lacking, missing, or absent — to fall short of what is needed or expected. It appears in both literal and theological contexts to describe absence or deficiency.
The theological use of adar touches on the concept of accountability before God. In Isaiah 40:26, God calls out the stars and 'not one of them is missing' — a declaration of His perfect sovereignty over creation. What God establishes, He maintains; nothing falls short of His design. This contrasts sharply with human shepherds and leaders who adar — fail to show up, fall short of responsibility, leave the flock abandoned. Ezekiel's devastating indictment of Israel's shepherds (Ezekiel 34) draws on this concept. The promised Good Shepherd (John 10:11-18) stands as the ultimate fulfillment: one from whose flock nothing is adar — 'I have not lost one of those you gave me' (John 17:12).