tie up is a verb meaning "secure with or as if with ropes". It carries 5 recorded senses.
invest so as to make unavailable for other purposes
“All my money is tied up in long-term investments”
restrain from moving or operating normally
“Traffic is tied up for miles around the bridge where the accident occurred”
Definitions, synonyms and semantic relations for tie up come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.