In geometry, what is an odd vertex???

Question

When looking at networks, I see that there are some vertices. I don't get what an odd vertex is!! is it the number of vertices which is an odd number?? or is it some kind of special vertex?? i dont get this at all!! please help!!

here is a picture of some networks. Do any of them have any odd vertices?? is so, please explain how !! ty x

http://people.hofstra.edu/geotrans/eng/ch2en/conc2en/img/nblinksnet.gif

Answer 1

Presumably, it means a vertex with an odd degree. The degree of a vertex is the number of edges connecting to it.