What are Solana killers?

Could you elaborate on what exactly "Solana killers" refer to? I've been hearing this term quite often in the crypto circles but haven't quite grasped its full meaning. Is it related to some sort of competitive threat to the Solana blockchain? Or does it refer to projects that aim to outperform Solana in some key metrics? I'm curious to know if there are specific features or advantages that these "killers" possess that make them stand out. It would also be helpful to understand the context behind this term and how it's being used in the larger crypto ecosystem. Could you please provide some insights?