the.com/flaw

means A flaw is an imperfection or weakness — a crack, defect, or failing in character, material, or plan.

from From Old Norse 'flaga,' meaning a slab, flake, or chip of stone — something that had splintered off and was no longer whole. Middle English picked it up as 'flaw' to mean a sudden gust or burst, then a crack or breach, and eventually any flake or fault in a surface. By the time it reached people's characters rather than ice and stone, it had kept that sense of something chipped away, a break in what should have been solid.