A bit of dust is a very small particle of matter, usually consisting of tiny particles of dirt, sand, or other materials. The term 'bit of dust' can be broken down into three crossword solutions: MOTE (4 letters), SPECK (5 letters), and SMOTE (5 letters). MOTE is a very small particle, such as a SPECK of dust, while SPECK is a small spot or mark, and SMOTE is to strike or hit something. All three words are related to the term 'bit of dust' and can be used to describe a very small particle of matter.