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 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.

I can't stand his idle and incompetent attitude.

He listened to the news with an apathetic face.