dictionary.reference.com/browse/Horizontal Line

www.mathopenref.com/horizontal.html

In geometry, a horizontal line is one which runs from left to right across the page. It comes from the word 'horizon', in the sense that horizontal lines are parallel to ...

www.mathopenref.com/coordhorizontal.html

Definiton and equation for a horizontal line in coordinate geometry.

www.virtualnerd.com/algebra-1/linear-equation-analysis/intercept/horizontal-vertical-lines/horizontal-line-definition

It's a horizontal line! And just like the horizon, horizontal lines go straight left and right. In this ... definition; horizontal; graph; graphical; equation; horizontal; flat.

study.com/academy/lesson/what-are-horizontal-lines-definition-equations-quiz.html

In this lesson, we will learn about horizontal lines. What properties are unique to horizontal lines? How do you recognize the graph or equation...

www.mathsteacher.com.au/year8/ch15_graphs/05_hor/ver.htm

Plotting a horizontal line and plotting a vertical line.

www.mathsisfun.com/definitions/horizontal.html

Definition of. Horizontal. Horizontal. Going side-to-side, like the horizon. Parallel to the horizon. (Up-down is called vertical). See: Vertical ...

www.investopedia.com/terms/h/horizontal-line.asp

DEFINITION of 'Horizontal Line'. In finance and economics, a horizontal line is usually the X axis in a data plot. It is a line that appears to proceed from left to right ...

www.mathwords.com/h/horizontal_line_test.htm

Note: The function y = f(x) is a function if it passes the vertical line test. It is a one- to-one function if it passes both the vertical line test and the horizontal line test.

www.coolmath.com/algebra/08-lines/08-graphing-horizontal-vertical-lines-01

What if we want to graph this? Hmm... It doesn't look like there's enough there! Where's the x? We're used to these: