# Boundary

Pronunciation: /ˈbaʊn.dri/ Explain

In general, the word boundary refers to the part of a math object between things that are part of the math object and things that are not part of the math object. For more specific information, see one of the following articles:

• Geometry - A boundary of a geometric figure is the set of points between the interior of the figure and the exterior of the figure.
• Sets of numbers - A boundary of a set of numbers is either a least upper bound, or a greatest lower bound. A least upper bound is the least number that is greater than or equal to all numbers in the set. A greatest lower bound is the greatest number that is less than or equal to all numbers in the set.

### References

1. McAdams, David E.. All Math Words Dictionary, boundary. 2nd Classroom edition 20150108-4799968. pg 27. Life is a Story Problem LLC. January 8, 2015. Buy the book

• McAdams, David E.. Bound. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 6/21/2018. http://www.allmathwords.org/en/b/bound.html.
• McAdams, David E.. Set. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 6/22/2018. http://www.allmathwords.org/en/s/set.html.