verb to load or weigh down with a heavy or oppressive burden
adjective feeling or having a heavy burden or load
noun A word that represents a person, place, thing, or idea. In this case, 'case' is a noun as it refers to a particular situation or instance.
adjective A word that describes or modifies a noun. In this case, 'sad' is an adjective that describes the noun 'case' as being characterized by sorrow or unhappiness.