The crossword solution for the term SUBSTANTIAL, AS SUMS is TIDY, which is a four-letter word. TIDY means to put things in order, to make neat and orderly, or to be clean and organized. It can also refer to a person who is neat and orderly in their habits. Substantial, as sums, refers to a large amount of money or resources. Therefore, the phrase 'substantial, as sums' could be used to describe a large sum of money that is well-organized and TIDY.