Use a carpenter's level.
A collar tie
Check out "horizontal cylindric segment" in Wolfram Alpha Online. That is the correct term for the solid you are looking for. Wolfram Alpha - "The solid cut from a horizontal cylinder of length L and radius R by a single plane oriented parallel to the cylinder's axis of symmetry (i.e., a portion of a horizontal cylindrical tank which is partially filled with fluid) is called a horizontal cylindrical segment."
Horizontal.
Framing
It is called a horizontal line!
Yo use a spirit level
Either s level or s plumb bob!
Web definition: the horizontal framing member between a door and a window above; also refers to the window above a door.
Portrait is vertical format.Landscape is horizontal format.
horizontal
The purlin is the framing member the roofing sheets screw to.
kING STUD
The horizontal member that bears the upright portion of a frame, especially the horizontal member that forms the base of a window.
The horizontal member that bears the upright portion of a frame, especially the horizontal member that forms the base of a window.
Its the bottommost horizontal member.
transom
the boom