The term "rare" has several meanings, depending on its context.
1) In a general sense, rare refers to something that is scarce or difficult to find; uncommon. For example, "This bird species is considered rare because there are only a few of them left in the wild."
2) Rare can also be used to describe an event or situation that happens infrequently. For instance, "It's rare for me to miss my bus stop."
3) In medicine, rare refers to a condition or disease that affects a small percentage of the population. For example, "This genetic disorder is so rare that only a few hundred people worldwide are known to have it."