What word is synonymous with 'to weaken' or 'to make thinner'?

The answer is macerate, which means to soften or break down food or material, often by soaking it in liquid, effectively making it thinner or weaker in structure. This term is commonly used in culinary contexts, such as when fruits are macerated in sugar or when bones are softened through a process that breaks down their structure.

The other options do not convey the same meaning. Maunder refers to speaking in a rambling manner or wandering. Maculate means to mark with spots or stains, which is unrelated to the concept of weakening. Ossified describes something that has become rigid or hardened, typically in a biological context, and does not relate to thinning or weakening either.