Examples:

bar graph  A graph in which the lengths of horizontal or vertical bars represent the magnitude of the data represented.

base  See exponential notation.

base of parallelogram  One of the sides of a parallelogram; also, the length of this side.  The shortest distance between the base and the side opposite the base is the height (or altitude) of the parallelogram.

base of a polygon  The side on which the polygon “sits;” the side that is perpendicular to the height (or altitude) of the polygon.

base of a polyhedron  The “bottom” face of a polyhedron; the face whose shape is the basis for classifying a prism or pyramid.

base of a rectangle  One of the sides of a rectangle; also, the length of this side.  The length of the side perpendicular to the base is the height (or altitude) of the rectangle.

base of a 3-dimensional figure  One face or a pair of faces on the figure.  The height (or altitude) is the length of a line segment drawn perpendicular to a base of the figure which extends from that base to an opposite face or vertex.

base of a triangle  One of the side of a triangle; also, the length of this side.  The shortest distance between the base and the vertex opposite the base is the height (or altitude) of the triangle.

base ten  The familiar numeration system (also called the decimal numeration system), consisting of the ten digits 0, 1, 2, …, 9 and a method of assigning values to these digits depending on where they appear in a numeral (ones, tens, hundreds, and so on, to the left of the decimal point; tenths, hundredths, and so on, to the right of the decimal point).

benchmark  An important or memorable count or measure that can be used to evaluate the reasonableness of other counts or measures.

billion  A digit or digits followed by 9 whole-number places.  One billion written in number form is 1,000,000,000 or 10⁹.

bisect  To divide a segment, angle, or figure into two parts of equal measure.

braces  See grouping symbols.  The symbols { and }.

brackets  See grouping symbols.  The symbols [ and ].

braking distance  The distance a car travels from the time the brake pedal is pressed to the time the car comes to a complete stop.

broken-line graph  See line graph.