half-

prefix

Etymology: From Middle English half-, from Old English healf-, from Proto-Germanic *halba- (“half-”), from *halbaz (“half”). Cognate with Dutch half- (“half-”), German halb- (“half-”), Swedish halv- (“half-”), Icelandic hálf- (“half-”). More at half.

1. half or partial; not complete
2. Used before brother, sister, uncle, aunt, and so forth, to indicate that the person being identified is related only through one parent, grandparent, and so forth, rather than two.