Other forms: forbearingly
You are forbearing if you're very forgiving and patient. A strict teacher might punish a noisy class, but a forbearing teacher will give everyone a few minutes to quiet down.
It may be frustrating to watch small children argue about whose turn it is to choose a bedtime story, but if you're a forbearing babysitter, you'll wait calmly while they sort it out—and then you might offer to read them two books. The Old English source of this tolerant adjective is forberan, "control one's feelings or endure."