three-quarter sibling

noun4

1. •
   A sibling with whom one shares about 37.5% of one's genes, as opposed to 25% for half-siblings and 50% for full siblings.
2. •
   The offspring of a horse's sire/dam that is by/out of a sibling of its other parent.
3. •
   The offspring of a horse's dam and a son of its sire.
4. •
   The offspring of a horse's sire and a daughter of its dam.