An undirected graph is a type of graph where the direction of the edges is not specified.

He is a reticent person, so he doesn't talk much.

He has a reticent personality and doesn't talk much.

This discussion is completely meaningless.

His talk was completely nonsense.

This medicine has become ineffective.

There are many beautiful cherry trees on the other side of the mountain.

He was peeling an apple.

He was unconsciously humming the tune.

He is known as an idle and incompetent employee.