"Most reappeared" is a term that implies an event or phenomenon occurring multiple times. Its antonyms would be words that indicate uniqueness or rarity. Some examples of such antonyms include 'once-in-a-lifetime,' 'uncommon,' 'infrequent,' 'rare,' and 'seldom.' While 'most reappeared' signifies a significant or noteworthy recurrence, its antonyms signify an exceptional occurrence that is not often seen or experienced. Other potential antonyms could include 'unexpected,' 'surprising,' 'isolated,' or 'occasional.' Overall, given the associations with repetition and frequency, the antonyms of 'most reappeared' seek to highlight the idea of rarity, singularity, or surprise.