Definition: Familiar friends, neighbors or relatives.
Kith has had many meanings over the years. In its earliest uses it referred to knowledge of something, but that meaning died out in the 1400s. Another sense, "one's native land," had come and gone by the early 1500s. The sense "friends, fellow countrymen, or neighbors" developed before the 12th century and was sometimes used as a synonym of kinsfolk. That last sense got kithinto hot water after people began using the word in the alliterative phrase "kith and kin." Over the years, usage commentators have complained that kithmeans the same thing as kin, so "kith and kin" is redundant. Clearly, they have overlooked some other historical definitions, but if you want to avoid redundancy charges, be sure to include friends as well as relatives among your "kith and kin."