Inch : An inch or $in$ is a unit of measurement for length. 12 inches are one foot and 1 inch is about 2.54 $cm.$

Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.

Measurement : To measure something or to get a measurement is to quantify a physical attribute given a choice of unit using the appropriate tool for measuring that specific physical attribute (for example a scale for weight or a measuring tape for length).

Meter : A meter is a unit for measuring length.

Unit : When measuring an attribute a particular unit specifies which size of the specific attribute is represented by the number 1. For example 1 $cm$ equals 10 $mm$, so when changing the unit we will also have to change the quantity to still represent the same measurement.

Weight : Weight refers to the property of objects that can be measured with a scale.

Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Multiple : A multiple of a number $x$ is any of the numbers $1x,2x,3x,4x,\ldots.$ For example the multiples of 7 include 7, 14, 21 and 70.

Expression : An expression is a succession of constants, variables and mathematical operations that if evaluated for specific values of the variables represents a number.