In Geometry, we have several undefined terms: point, line and plane. From these three undefined terms, all other terms in Geometry can be defined. A line is defined as something that extends infinitely in either direction but has no width and is one dimensional while a plane extends infinitely in two dimensions.Click to see full answer. Besides, what is the 3 undefined terms in geometry?In geometry, formal definitions are formed using other defined words or terms. There are, however, three words in geometry that are not formally defined. These words are point, line and plane, and are referred to as the “three undefined terms of geometry”. a point has no length, no width, and no height (thickness).Also Know, what are examples of undefined terms? For example, in (Euclidean) geometry, the terms “point” and “line” are undefined terms that name objects in the universe of discourse, while “on” is an undefined term that names a relation. In older texts, (or those written by less mathematically aware authors) an attempt to define such terms was made. Subsequently, question is, why are they called undefined terms in geometry? We are not talking undefined in the sense that we would expect, but undefined in a different sense. These four things are called undefined terms because in geometry these are words that don’t require a formal definition. They form the building blocks for formally defining or proving other words and theorems.What is defined terms in geometry?In geometry, defined terms are terms that have a formal definition and can be defined using other geometrical terms.