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.
- A prefix 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.
- A prefix used to indicate that something is just half or done half, and therefore not total or fully done.
- quarter- (prefix for a fourth part)