The scientist made groundbreaking discoveries but remained uncelebrated during his lifetime.

uncelebrated 是由前缀 un-（表示"不、非"）和动词 celebrate（庆祝、赞美）的过去分词 celebrated 组成的形容词。celebrated 意思是"著名的、受赞誉的"，加上否定前缀 un- 后表示"未被赞颂的、默默无闻的"。