Definition for Clubbed thumb
From Biology Forums Dictionary
A clubbed thumb is brachydactyly type D or BDD of the thumb, a genetic trait characterized by one or both thumb nails being clubbed and the thumbs being fat and round.
The condition is sometimes known as murderer's thumb, a name originally coined by gypsy fortune tellers or potter's thumb. More recently, it has been referred to as toe thumb for its resemblance to the big toe.