Accountability is the condition of being answerable — obliged or willing to give an account of one's actions, decisions, and outcomes to someone with standing to ask.
The word is a late arrival. Accountable enters English around 1400 from Old French acontable, meaning "answerable" and literally "liable to be called to account" — the underlying image is bookkeeping, a reckoning that someone else is entitled to inspect. The abstract noun follows much later: accountableness in the 1660s, and accountability itself only by 1770. The institutional apparatus the word now implies — audits, disclosure regimes, oversight bodies, reporting lines — is younger still, and in governance the term carries the specific claim that power must be answerable to those it is exercised over.
Accountability is often used interchangeably with responsibility, but the two point in different directions. Responsibility is about ownership: whose job it is. Accountability is about answerability: who must explain the result, and to whom. Work can be distributed across many hands while accountability stays with one — and when it is assigned to no one in particular it tends to evaporate, the group dynamic named by 📝Diffusion of Responsibility. It is also distinct from blame, with which it is routinely confused. Blame terminates in a verdict; accountability terminates in an account, which may lead to correction, restitution, or nothing at all. That difference is why contemporary organizational usage frames accountability as a condition for learning rather than a mechanism for punishment.