phrasal verbto attach or to fasten something tightly ExamplesThe parcel is tied up with string. • The ship was tied up to the quay.to invest money in one way, so that it cannot be used for other investments ExamplesHe has £100,000 tied up in long-dated gilts. • The company has £250,000 tied up in stock which no one wants to buy."...a lot of speculator money is said to be tied up in sterling because of the interest-rate differential between US and British rates" [Australian Financial Review] to attach or to fasten something tightly to invest money in one way, so that it cannot be used for other investments