The meaning of Erastus is Lovely and  Beloved. Its origin is Variant of the Greek name Erastos. Erastus is a form of Erastos and is generally pronounced like eh RAS tus. This name is mostly being used as a boys name. Last year it ranked 4,160th in the U.S. Social Security Administration list of most popular baby boy names.
Which undefined term is needed to define an angle? Plane Point Ray Line. Undefined, you need a line to define an angle (if you're looking for undefined terms). This is because, if you think about it, a ray is part of a line.
angle - the space between two lines or planes that intersect; the inclination of one line to another; measured in degrees or radians