Used as '〜なしで' to mean 'without' (in the absence of). Common in both spoken and written Japanese; often follows a noun or phrase.
事前の説明なしで会議を始めるのはよくない。
It's not good to start a meeting without prior explanation.
このサービスは登録なしで利用できますか？
Can this service be used without registration?
保証書なしで修理に出すと受け付けてもらえない場合がある。
If you send it for repair without a warranty, it may not be accepted.