means To make a firm decision and stick to it, or to settle a problem or dispute so it stops being a problem.

from From Latin 'resolvere,' literally 'to loosen back, to untie' — built from 're-' (back) and 'solvere' (to loosen, release), the same 'solvere' that gives us 'solve' and 'dissolve.' The original sense was almost the opposite of firmness: to melt, dissolve, break a thing into its parts. Over centuries the meaning swung from 'breaking apart' to 'settling' — first untangling a confusion into clarity (resolving a question), then hardening that clarity into a fixed decision (resolving to act). So the word that once meant coming undone now means refusing to.