1. To wrap a line around something in order to anchor it. A noun or pronoun can be used between "snub" and "up." We need to snub the trees up around the property so they don't get blown down by the storm coming through. Jump onto the pier and snub up the boat to one of those mooring posts.
2. To make something secure or stable. A noun or pronoun can be used between "snub" and "up." As an emergency measure, the Federal Reserve dropped interest rates to record lows as a means of snubbing up an already faltering economy.
To anchor something, such as a vessel, by wrapping a line around a post or cleat: The dock workers took a line and snubbed up the boat. I snubbed the boat up and went ashore. As we came in, one of the crew jumped onto the pier, grabbed a line, and snubbed up.