The Spanish verb 'desquiciar' (meaning 'to unhinge' or 'to unsettle') has an interesting evolution from Vulgar Latin. It starts with the Vulgar Latin word 'excrepitiare' meaning 'to crack or split'. This evolved into the Spanish word 'resquicio' meaning 'gap or crack', which then gave rise to 'quicio' meaning 'hinge or pivot'. The modern verb 'desquiciar' was formed by combining the prefix 'des-' (indicating reversal or negation) with 'quicio' and the verb suffix '-ar', literally meaning 'to remove from its hinges' and by extension 'to unsettle or disturb'.

A simpler related Spanish word is 'quicio' meaning 'hinge' or 'pivot', which is the base word from which 'desquiciar' is formed. Another related word is 'resquicio', meaning 'gap' or 'crack', which preserves more of the original Latin meaning of splitting or cracking. When you see these words together, you can understand how the idea of a hinge or pivot point evolved from the concept of a crack or gap, and how removing something from its hinge ('desquiciar') came to mean unsettling or disturbing something from its normal state.

While there aren't direct English cognates from the same Latin root 'excrepitiare', English speakers can understand the metaphorical connection between 'unhinging' something and making it unstable or disturbed. In English, we also use 'unhinged' metaphorically to describe someone who is mentally disturbed or unstable, parallel to how 'desquiciar' can mean to unsettle or disturb in Spanish.