We can use this word to describe the figure. For example, the sentence "her waist is thin" means "her waist is as thin as a bundle". You can also describe the food, for example, "the soup is too thin" means "this soup is too thin". Besides, it can also be used to describe weather words, such as "mist", which means "the fog is thin".
Thin can also be used as a metaphor. For example, "thin air" means "nothing in the air"; "Thin ice" means "walking on thin ice". In this case, "thin" describes an unreal, uncertain or dangerous situation. These are some common descriptions of this word in everyday English.