1) A lanyard (or leash if you prefer) applied to something you wish to keep on your person while you perform acts which may result in said object's irrevocable loss.
Ex: Tying a length of paracord to your fishing knife so if you drop it, it won't plunge to the bottom of the ocean, thereby leaving you to cut that salt encrusted bowline with your teeth.
2) The act of applying such a lanyard to your equipment.
1) "Ya got some dummy cord? I don't want to lose my compass when we jump."
2) "Dummy cord that radio for me so we don't lose it when we hit the surf zone."