limbic adj.

late 14c., "edge of a quadrant or other instrument," from Latin limbus "ornamental border, hem, fringe, edge," a word of uncertain origin. Klein suggests it is cognate with Sanskrit lambate "hang down limply" and English limp (adj.). Tucker writes that "the sense appears to be that of something which twists, goes round, or binds ... not of something which hangs loose," and suggests cognates in Lithuanian linta "ribbon," Old Norse linnr "whether." De Vaan tends to agree with Klein and writes, "In view of the phoneme *b, the very specific meaning of limbus and its absence from the oldest literature, the etymology remains uncertain." Astronomical sense of "edge of the disk of a heavenly body" first attested 1670s. Related: Limbal.