Commonly it's "leiwond" or "leiwaund" and it is a very frequently used term. You would hear it very often here. :-)

Since it's a colloquial expression, it may be spelled variously as "leinwand", "leiwand", "leiwond" or even "leiwaund" (or so google tells me). It used to be "(die) Leinwand", which originally only meant "linen" and later usually meant "screen" (as in a cinema).