UN is a prefix meaning ‘not’. See PREFIX. For example uncertain means not certain and unworried means not worried.

UNAWARE – (adjective) is the opposite of aware. See AWARE. “He crept up behind her so quietly that she was unaware of his presence. The blind person was unaware that she had come into the room.

UNCONSCIOUS – (adjective) means not aware or not conscious. See CONSCIOUS and AWARE. “When he was hit on the head he went unconscious for an hour. When he woke up again he did not know what had happened to him”.

UNIT – (noun) 1. A unit is an amount used for measuring. A centimetre, a meter and a kilometre are all units of length. A square meter is a unit to measure area. A second is a unit to measure time. 2. Unit also means the smallest whole number, which is 1. 3. In the plural units means the numbers from 1 to 9 but less than 10. In the number 564 there are 5 hundreds, 6 tens and 4 units. 4. A unit is also a group of people or things which one thinks of as one thing. A team is a unit. A family is a unit, but be careful because one can also speak of the units that make up a whole thing. So one could say the father, the mother and the children are the units that make up a family unit.

UNITS is the plural of unit. See UNIT. When you use the word units in maths you often mean the place in a number where the unit’s digit is. In the following number the digit 7 is in the units place, the 5 is in the tens place and the 1 is in the hundreds place: 157.

UNIVERSE – (noun) A universe is a system of created things. See SYSTEM & CREATE. A universe consists of space with energy and matter in it and time. The space of our universe has 3 dimensions. See DIMENSIONS.

UNKNOWN – (noun) An unknown is something which is not known. See CO-EFFICIENT. In algebra the unknown numbers are usually represented by letters near the end of the alphabet. X, Y and Z are usually the unknowns. By using the methods of algebra the values of the unknowns can be found out.

UNLIKE – (adjective) means not alike or not the same. “We have unlike weights; I am fat and she is thin.

USUAL – (adjective) 1. Usual and normal have similar meanings. The usual way is the way things are or happen in everyday life.” It is usual for people to work during the day and sleep at night. It is usual to have cold weather in winter and hot weather in summer. ” 2. As usual means in the usual way.” As usual she does not believe what I tell her. ” As usual and usually have very similar meanings. “ Usually I get up at 6 am.