"impend or hang over," hence "threaten," 1590s, from over- + hang (v.). Related: Overhung; overhanging (by 1560s). Middle English had overhongen "to hang over (something)," late 14c.
overhang (n.)
1864, "a projecting part;" 1883, "fact of overhanging," from overhang (v.).
overgraze
overground
overgrown
overgrowth
overhand
overhang
overhasty
overhaul
overhead
overhear
overheat