A thimbleful is a small amount of liquid, usually referring to an alcoholic beverage. It is derived from the word thimble, which is a small cup-shaped tool used for measuring and pouring out small amounts of liquid. The term 'thimbleful' can be broken down into three crossword solutions: TAD (3 letters), NIP (3 letters), and SIP (3 letters). A TAD is a small amount, a NIP is a small drink, and a SIP is a small taste. Together, these three words form the term 'thimbleful, ' which is a small amount of liquid.