Other forms: helder
Anything that's held is controlled or kept by someone (or something). A city, for example, might be held by an attacking army.
A rebel-held town is occupied by an invading group of rebels, and a Republican-held government is controlled by that particular political party. When Americans win so many medals in the Olympics that they break a world record, you might hear it described as a US-held record. Held comes from the Old English haldan, "to possess, contain, or rule."