[noun]Lengths of laid ricestrawrope used for ritualpurification in Shintoshrines. They can vary in diameter from a few centimetres to several metres, and are often seen festooned with shide. A space bound by shimenawa often indicates a sacred or pure space, such as that of a Shinto shrine.
(This term, しめなわ(shimenawa), is the hiragana spelling of the above term.)