ONLINE GLOSSARY

0-9 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

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• Oblique. (Pronounced "oh-BLEEK") Not parallel to any normal view (as in an oblique line or oblique plane). Also, not upright, or appearing to "lean" to one side (such as an oblique cylinder, oblique cone or oblique prism).
  
  
• Oblique Cone. A cone that appears to "lean" to one side. If a line is drawn from the tip of such a cone to the exact center of the circular base, it will not be perpendicular to the plane containing the base.
  
  
• Oblique Cylinder. A cylinder that appears to "lean" to one side. The ends of such a cylinder are parallel to each other and cut at an angle so they are not perpendicular to the longitudinal axis of the cylinder.
  
  
• Oblique Line. A non-normal line that is not parallel to any principal plan view. An oblique line appears foreshortened in all normal views.
  
  
• Oblique Parallelepiped. (Pronounced "oh-BLEEK pair-uh-lel-uh-PIPE-id") A six-sided, three-dimensional shape very similar to a cube but where each side is a rhombus rather than a square.
  
  
• Oblique Plane. A non-normal plane that is not parallel to any principal plan view. An oblique plane appears foreshortened in all normal views.
  
  
• Oblique Prism. A prism that appears to "lean" to one side. The ends of such a prism are parallel to each other and cut at an angle so they are not perpendicular to the longitudinal axis of the prism.
  
  
• Octahedron. A three-dimensional geometric shape having 8 faces where each face is in the shape of a triangle. An octahedron can be assembled from two square-base pyramids.
  
  
• Odd Angle. Any angle that is not commonly used in construction. Common angles include 90 degrees, 60 degrees, 45 degrees, 30 degrees, 22.5 degrees (or 1/2 of 45 degrees), and 15 degrees. Most angles chosen in construction come from this list of commonly used values, are multiples thereof, or are otherwise rounded to the nearest five degrees. Any other choice might be considered an odd angle.
  
  
• Order of Importance. A principle used to decide which lines to show and which to omit when lines overlap in a drawing. Visible lines must always be shown and therefore have priority over all other line types. Hidden lines are next in priority, while centerlines are last.
  
  
• Orthographic Projection. A method whereby a subject can be drawn from any angle without including the distortion caused by visual perspective. The process of preparing orthographic plan views of a subject is also known as multi-view drawing. An imaginary "glass box" is said to surround the subject and views of the object are projected onto each side of the box. It is then "unfolded" so that all views are in the same plane.

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0-9 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

Click on a letter to browse through the Glossary terms.
To download a printable version of the entire Glossary, click here.

All written content on this page © 2007 Charles Adams. ALL RIGHTS RESERVED.
Reproduction, in whole or in part, is prohibited without written permission from the publisher.