There are numerous synonyms that can be used in place of the word "multitudes." Some of these synonyms include a crowd, a throng, a horde, a mass, a group, a mob, an assembly, or a congregation. Each of these words conveys the idea of a large group of people gathered together in one place. Depending on the context in which the word is used, one synonym may be more appropriate than another. For example, a "throng" might imply a group of people moving together in a somewhat chaotic manner, while an "assembly" might suggest a more organized gathering.