Congestion spot is a term used to describe an area where traffic is particularly dense and slow-moving. The crossword solution for this term is SINUS, which is a Latin word meaning 'curved cavity'. This term is often used to refer to the nasal cavities, but it can also be used to describe any curved or hollow space. In this context, congestion spot could refer to a road or highway that has a lot of traffic, making it difficult to navigate.