patience: holding back anger or judgment over a long stretch of time, whether by not retaliating against those who wrong you or by waiting calmly through a long delay
The Greek word literally means something like "long-tempered": a person whose anger takes a long time to catch fire, the opposite of someone who is quick to flare up. In ordinary Greek it was a thin, rarely used word, but the early Greek translation of the Old Testament made it carry the full weight of how God describes himself. When God reveals his own character to Moses he calls himself "slow to anger" (Exodus 34:6), and that phrase became one of his fixed titles. So by the time the New Testament writers use this word, it already means God's deliberate choice to put off the punishment people deserve, giving them room to turn back to him.
From that one core, the word stretches in two directions that the New Testament uses interchangeably. Most often it means patience toward people: refusing to hit back at someone who wrongs you, bearing with a difficult person rather than exploding in anger or seeking revenge. This is the patience God shows sinners, the patience Christ showed even to the man who persecuted his followers, and the patience believers are told to show one another. Less often the same word leans toward patient waiting: holding on through a long delay until a promise finally arrives, as Abraham waited for the son he was promised and as farmers wait for the harvest.
These are not two unrelated ideas but one disposition seen from two angles. In both, something is being held back: in the first, deserved anger; in the second, the impatience that wants relief now. That is why the same writers can place this word beside endurance to cover both bearing with people and bearing up under hard circumstances. The thread running through every use is that this patience is patterned on God: believers are asked to extend to others the same long forbearance God has first extended to them.