The Hebrew word arubbah (אֲרֻבָּה) refers to a window, lattice, sluice, or opening — any aperture that allows the passage of light, air, smoke, or water. It describes chimney openings, the windows of heaven through which rain descends, and lattice windows in buildings.
The most theologically significant use of arubbah is Malachi 3:10's 'windows of heaven' — God's promise to 'open the floodgates/windows of heaven' and pour out blessing so abundant there is not room enough for it, if His people bring the full tithe. This imagery of divine abundance flowing through heavenly apertures speaks to God's unlimited capacity to bless. The arubbah of heaven is not a trickle but a flood. Genesis also uses this word for the 'floodgates of heaven' opening during Noah's flood — the same channel that brings judgment can become the channel of blessing.