Someone who's long-suffering puts up stoically with discomfort, trouble, or other people's bad behavior. Your patient old dog, who calmly endures the hugs and ear-tugs of little kids, is long-suffering.
If someone is described as a long-suffering wife or husband, the implication is that this person has put up with a stubborn, frustrating, or cranky spouse for many years — without complaining. The long-suffering fans of a losing baseball team, on the other hand, keep on rooting enthusiastically for them despite their disappointing record. This adjective has existed in English since the 16th century.