tie up in WordNet English dictionary

1. secure in or as if in a berth or dock
   "tie up the boat"
   moor  berth  tie up 
   
2. secure with or as if with ropes
   "tie down the prisoners"; "tie up the old newspapers and bring them to the recycling shed"
   tie down  tie up  bind  truss 
   
3. finish the last row
   tie up  bind off 
   
4. restrain from moving or operating normally
   "Traffic is tied up for miles around the bridge where the accident occurred"
   tie up 
   
5. invest so as to make unavailable for other purposes
   "All my money is tied up in long-term investments"
   tie up 
   

tie up in English Wiktionary