Accumulation of refuse is a term used to describe the buildup of waste materials, such as scrap metal, paper, plastic, and other garbage. This can be seen in the two crossword solutions, 'scrapheap' and 'rubbishheap, ' which both refer to large piles of discarded items. Scrapheap is a nine-letter word, while rubbishheap is an eleven-letter word. Both words are used to describe the same phenomenon, but the longer word implies a larger accumulation of refuse.