The word 只是 is formed through the conceptual combination of its two component characters: 只, which carries the inherent meaning of "only", "merely", or "just", and 是, which fundamentally means "is" or "this". When fused, the literal notion of "only this is" evolves into a single, cohesive idea used to express limitation, exception, or a gentle contradiction, meaning "it's just that" or "merely".