The Greek adjective akatastatos means 'unstable,' 'restless,' or 'inconstant' — the opposite of settled, ordered, and reliable. Formed from the alpha-privative and kathistēmi (to set in order), it describes a person or thing that lacks the stability and reliability of proper ordering. It appears in James 1:8 and 3:8.
James uses akatastatos with surgical precision. The double-minded man (James 1:8) is 'unstable in all his ways' — his divided loyalty between God and the world makes him unreliable in every aspect of life. Then in James 3:8, the tongue is described as 'a restless (akatastaton) evil, full of deadly poison' — it cannot be tamed precisely because it reflects the instability of a heart not fully surrendered to God. The word appears in the Septuagint to describe the chaos of ungodly nations (Isaiah 54:11) and the restlessness of the wicked (Isaiah 57:20). The antidote to akatastatos is the stability found in God — the Rock who does not shift, the anchor for the soul (Hebrews 6:19).