EnchantedLearning.com is a user-supported site.
As a bonus, site members have access to a banner-ad-free version of the site, with print-friendly pages.

 You might also like: Y: Illustrated Math Dictionary - Enchanted Learning.com X: Illustrated Math Dictionary - Enchanted Learning.com D: Illustrated Math Dictionary - Enchanted Learning.com H: Illustrated Math Dictionary - Enchanted Learning.com M: Illustrated Math Dictionary - Enchanted Learning.com Today's featured page: Animal Poem

 +, - EnchantedLearning.comMath Dictionary x, ÷
 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 O is for ...
 obeliskAn obelisk is a tall, four-sided tower topped with a pyramid. obliqueLines or planes are oblique when they are neither parallel nor perpendicular to each other. obtuse angleAn obtuse angle is an angle greater than ninety degrees. obtuse triangleOne of the interior angles of an obtuse triangle is obtuse ( an obtuse angle is over 90 degrees).
 octadecagonAn octadecagon is an eighteen-sided figure. octagonAn octagon is an eight-sided figure. Stop signs are octagons. octahedronAn octahedron is an eight-sided geometric solid (a 3-D object). 1, 3, 5, 7, 9, 11, ...odd numberAn odd number is not divisible evenly by two.
 oneOne is the number between zero and two. One is the multiplicative identity, since one times any number is equal to that number. 1/2one halfWhen something is divided into two equal parts, each of these two parts is one half of the original object. operationAn operation is a rule for taking one or two numbers as inputs and producing a number as an output. Some arithmetic operations are multiplication, division, addition, and subtraction. oppositesOpposites are things that are very, very different from each other. Some examples of opposites are: positive and negative, add and subtract, left and right, big and small, up and down.
 orbAn orb is a ball-shaped object. order of magnitudeThe order of magnitude is the estimate of size (or magnitude) expressed as a power of ten. For example, a 100 ft (102 ft) tall building one order of magnitude taller than a 10 ft (101 ft) tall building. order of operationsIn mathematical operations, the standard order of operations is: Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction. Within a category, operations are done from left to right. ordinal numberOrdinal numbers show order. Some ordinals are first (1st), second (2nd), third (3rd), fourth (4th), fifth (5th), sixth (6th), seventh (7th), eighth (8th), ninth (9th), tenth (10th), eleventh (11th), twelfth (12th), etc.
 ordinateOrdinate is another name for numbers on the y-axis (the vertical axis). The ordinate is the second number in a point (x,y). originThe origin is the point (0,0) -- where the x and y axes meet. In a 3-d coordinate system, the origin is the point (0,0,0) -- where the x, y and z axes meet. ounceAn ounce is a unit of measure. Eight ounces are one cup. ovalAn oval is an egg-shaped figure.

 +, - EnchantedLearning.comMath Dictionary x, ÷
 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 Number Line Fractions Decimals Graphs Measurement Rounding

Click on an underlined word for more information on that subject. If the math term you are looking for is not in the dictionary, please e-mail us.

Enchanted Learning®
Over 35,000 Web Pages
Sample Pages for Prospective Subscribers, or click below

 Overview of Site What's New Enchanted Learning Home Monthly Activity Calendar Books to Print Site Index K-3 Crafts K-3 Themes Little ExplorersPicture dictionary PreK/K Activities Rebus Rhymes Stories Writing Cloze Activities Essay Topics Newspaper Writing Activities Parts of Speech Fiction The Test of Time iPhone app TapQuiz Maps - free iPhone Geography Game Biology Animal Printouts Biology Label Printouts Biomes Birds Butterflies Dinosaurs Food Chain Human Anatomy Mammals Plants Rainforests Sharks Whales Physical Sciences: K-12 Astronomy The Earth Geology Hurricanes Landforms Oceans Tsunami Volcano Languages Dutch French German Italian Japanese (Romaji) Portuguese Spanish Swedish Geography/History Explorers Flags Geography Inventors US History Other Topics Art and Artists Calendars College Finder Crafts Graphic Organizers Label Me! Printouts Math Music Word Wheels

## Enchanted Learning Search

 Search the Enchanted Learning website for: