The Collaborative International Dictionary of English v.0.48:

Ringtail \Ring"tail`\, n.
   1. (Zool.) A bird having a distinct band of color across the
      tail, as the hen harrier.
      [1913 Webster]

   2. (Naut.) A light sail set abaft and beyong the leech of a
      boom-and-gaff sail; -- called also ringsail.
      [1913 Webster]

   Ringtail boom (Naut.), a spar which is rigged on a boom for
      setting a ringtail.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ringtail
    n 1: raccoon-like omnivorous mammal of Mexico and the
         southwestern United States having a long bushy tail with
         black and white rings [syn: bassarisk, cacomistle,
         cacomixle, coon cat, raccoon fox, ringtail, ring-
         tailed cat, civet cat, miner's cat, Bassariscus
         astutus]
    2: North American raccoon [syn: common raccoon, common
       racoon, coon, ringtail, Procyon lotor]
    3: monkey of Central America and South America having thick hair
       on the head that resembles a monk's cowl [syn: capuchin,
       ringtail, Cebus capucinus]
    4: an immature golden eagle