What term describes something that provides stability or substance?

The term that describes something providing stability or substance is "ballast." In a broader sense, ballast refers to heavy material that is used to provide stability to a structure, such as a ship or a hot air balloon, ensuring that it remains upright and balanced. In various contexts, it can symbolize anything that adds weight or steadiness to a situation, making it more secure.

The other options do not convey the notion of stability or substance: "devout" pertains to being deeply religious or devoted, "scrupulous" refers to being careful and meticulous, often in moral contexts, and "pander" means to cater to the weaknesses or desires of others, which does not imply stability. Thus, "ballast" is the appropriate term that embodies the idea of providing stability.