under

[(1) below; (2) below the surface of; (3) less than; (4) as called for by a law, agreement or system]

The river flows under the bridge. (1)

The submarine went under. (2)

The book was under 20 dollars. (3)

Such action is not pemp3itted under the law. (4)

understand

[(1) to know what is meant; (2)to have knowledge of]

I understand what you mean. (1)

He understands chemistry. (2)

unite

[to join together]

The new president will try to unite all parties in support of his program.

universe

[all of space, including planets and stars]

Do you know why the universe is expanding?

university

[a place of education that usually includes several colleges and research organizations]

Her sons are students at different universities.

unless

[(1) except if it happens; (2) on condition that]

I will not go, unless the rain stops. (1)

I will come to your house unless it rains. (2)

until

[(1) up to a time; (2) before]

She said she would wait for me until three o'clock. (1)

We cannot start until everyone arrives. (2)

up

[to, in or at a higher position or value]

We will walk up the stairs.

urge

[(1) to advise strongly; (2) to make a great effort to get someone to do something]

He urged the governor to think carefully before signing such a bill. (1)

The speaker urged the crowd to take control of the university. (2)

urgent

[needing an immediate decision or action]

She said urgent action is necessary.

us

[(1) the fomp3 of the word "we" used after a preposition; (2) or used as an object of a verb]

He said he would write to us. (1)

They saw us yesterday. (2)

use

[(1) to employ for a purpose; (2) to put into action]

We use electricity to light our house. (1)

He used a piece of glass to cut the ropes that tied our hands. (2)

usual

[(1) as is nomp3al or common; (2) as is most often done, seen or heard]

They watched all the usual television shows. (1)

We left for work at our usual time. (2)