half blood

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The relationship existing between persons having only one parent in common.
2. n. A person existing in such a relationship.
3. n. Offensive A person of mixed racial descent, especially a person of Native American and white parentage.
4. n. A half-blooded domestic animal.

Century Dictionary and Cyclopedia

1. n. The relation between persons born of the same father or mother, but not of the same father and mother: as, a brother or sister of the half-blood.
2. n. One of two or more persons so related.
3. n. One born of a male and female of different breeds or races; a half-breed.
4. Having descent from one of the same parents as another, but not from both.
5. Belonging by blood half to one breed or race, and half to another.

Wiktionary

1. n. law A person shares one parent with another; a half-sibling.

GNU Webster's 1913

1. n. (Law) relationship through only one parent.
2. The relation between persons born of the same father or of the same mother, but not of both. See blood, n., 2 and 4.
3. A person so related to another.
4. A person whose father and mother are of different races; a half-breed.

WordNet 3.0

1. n. one of siblings who have only one parent in common