1600s

Thirteen of something rather than twelve, the extra item given as a small measure of good faith or generosity.

To be at loggerheads is to be locked in a stubborn dispute, unable to reach agreement with the other side.

A rough, practical method or principle based on experience and approximation rather than exact measurement or strict theory.

To turn a blind eye is to deliberately ignore something you know to be wrong, pretending not to notice it.

To bury the hatchet is to make peace with an adversary, settling a quarrel and agreeing to set aside past hostilities for good.

The very last moment of a difficult or unpleasant process, reached by continuing stubbornly until nothing whatever remains to be done.

On the whole or generally speaking; taking everything into account, a statement that is broadly true even if not correct in every detail.