The Scottish term for a low-lying meadow by a river is typically called a "haugh."
Playground, meadow, plaza.
skelp
bairn
Aside from the Latin, the most common term for lying on your back is supine.
Orthopnea is the medical term meaning shortness of breath when lying flat.
teuchter
bubbly jack
No, it's French.
The term is collinear.
philanthrope
Prone means lying horizontal with the face down. Pronation is the action of lying prone.