If you dreamed of the thumb, then such dream indicates the power and apprehends you put on certain things. To have very large thumb, means that you will succeed at everything you do. If you lost the thumb, then it symbolizes to losses and illness one will suffer. If you have a very long nails on your thumb, then it means that you will be trapped by those you have trusted. The metaphor ”under the thumb” would indicate the tendency to depend on others.