<WORD ID="1515" WORD="umbrella (n.)" EXPLANATION="a folding cover to protect a person from rain" EXAMPLE="If it's raining, take an umbrella." WAVE="UMBRELLA" />
<WORD ID="1516" WORD="unable (adj.)" EXPLANATION=" not able to" EXAMPLE="The singer is ill and is unable to perform." WAVE="UNABLE__" />
<WORD ID="1517" WORD="unbelievable (adj.)" EXPLANATION="unlikely to be true, hard to believe" EXAMPLE="We saw an unbelievable variety of flowers." WAVE="UNBELIEV" />
<WORD ID="1518" WORD="uncertainty (n.)" EXPLANATION="not being sure about something" EXAMPLE="His expression showed uncertainty. He couldn't make up his mind." WAVE="UNCERTAI" />
<WORD ID="1519" WORD="uncomfortable (adj.)" EXPLANATION="not comfortable" EXAMPLE="He wore uncomfortable shoes on the hike. Now his feet hurt." WAVE="UNCOMFOR" />
<WORD ID="1520" WORD="under (prep.)" EXPLANATION=" in a position lower than and covered by" EXAMPLE="We saw lions resting under a tree." WAVE="UNDER__A" />
<WORD ID="1521" WORD="underground (n.)" EXPLANATION="a railway under the ground in a city" EXAMPLE="The blue underground will get you to the market." WAVE="Undergrd" />
<WORD ID="1522" WORD="understand (v.)" EXPLANATION=" to be familiar with and know about, to know the meaning of something past: understood" EXAMPLE="I don't understand young people today, with their tattoos and strange clothes." WAVE="UNDERSTA" />
<WORD ID="1523" WORD="underwater (adj.)" EXPLANATION="beneath the surface and covered by water" EXAMPLE="He studied underwater photography. Now he makes nature films." WAVE="UNDERWAT" />
<WORD ID="1524" WORD="unforgettable (adj.)" EXPLANATION="not likely to be forgotten" EXAMPLE="We spent five unforgettable days seeing wild animals on the safari." WAVE="UNFORGET" />
<WORD ID="1525" WORD="unfriendly (adj.)" EXPLANATION="not kind" EXAMPLE="I thought he liked me, but the last time I saw him he was very unfriendly." WAVE="UNFRIEND" />
<WORD ID="1526" WORD="unhappy (adj.)" EXPLANATION="sad, not happy" EXAMPLE="The dolphins were unhappy because they were kept in a small tank." WAVE="UNHAPPY_" />
<WORD ID="1527" WORD="uniform (n.)" EXPLANATION="clothing which is the same for all people who work in a certain place or organisation" EXAMPLE="The Palace Guards wear special uniforms and tall black hats." WAVE="UNIFORM_" />
<WORD ID="1528" WORD="unique (adj.)" EXPLANATION="special, having no others like it" EXAMPLE="The unique materials used for the costumes are not found anywhere else" WAVE="UNIQUE__" />
<WORD ID="1529" WORD="united (adj.)" EXPLANATION="joined together into one" EXAMPLE="After a long separation, the mother and her children were united." WAVE="UNITED__" />
<WORD ID="1530" WORD="university (n.)" EXPLANATION="a school of higher learning that offers professional degrees in addition to college instruction" EXAMPLE="You can study Chinese in our university." WAVE="UNIVERSI" />
<WORD ID="1531" WORD="until (prep.)" EXPLANATION="up to the time of" EXAMPLE="No one knew where Machu Picchu was until Hiram Bingham found it in 1911." WAVE="UNTIL" />
<WORD ID="1532" WORD="untouched (adj.)" EXPLANATION="not changed or altered" EXAMPLE="This desert is still untouched by modern man." WAVE="UNTOUCHE" />
<WORD ID="1533" WORD="unusual (adj.)" EXPLANATION="not common, not usual, strange" EXAMPLE="Aren't these designs unusual? I've never seen anything like them." WAVE="UNUSUAL_" />
<WORD ID="1534" WORD="upper (adj.)" EXPLANATION="closer to the top" EXAMPLE="The upper floor of the museum is filled with Greek and Roman art." WAVE="UPPER__A" />
<WORD ID="1535" WORD="use (v.)" EXPLANATION="to employ for some purpose" EXAMPLE="Nobody knows exactly when people began to use skis, but it was a very long time ago." WAVE="USE__V__" />
<WORD ID="1536" WORD="usually (adv.)" EXPLANATION="most of the time" EXAMPLE="Lions usually hunt at night, but also sometimes in the daytime." WAVE="USUALLY_" />
