The term AS DUST DRY can be broken down into two crossword solutions: ARID (4 letters) and MOTE (4 letters). ARID is an adjective meaning 'extremely DRY, especially due to lack of rainfall'. It is derived from the Latin word aridus, which means 'DRY'. MOTE is a noun meaning 'a small particle of DUST or dirt'. It is derived from the Old English word mot, which means 'DUST'. Together, the two words describe a very DRY environment with a lot of DUST.