To allow (someone) to do as he or she pleases: left the child to her own devices for an hour. 2. To force (someone) to cope or manage without assistance: Most people would die in the desert if left to their own devices.
A device is a non-tangible or non-physical object, like a procedure, technique, or plan. For example, a mnemonic device helps you remember a shopping list or your friend's phone number.