The term 'Symbol of Solidity' can be represented by two crossword solutions: OAK (3 letters) and OAKTREE (7 letters). The OAK tree is a symbol of strength and endurance, and has been used throughout history to represent stability and solidity. It is a symbol of wisdom, strength, and protection, and is often seen as a symbol of courage and resilience. The OAK tree is also a symbol of longevity, as it can live for hundreds of years.