The word 海盗 is formed by directly combining two meaningful characters: 海 (hǎi), meaning "sea" or "ocean", and 盗 (dào), meaning "robber" or "thief". It is a conceptual compound where the first character specifies the domain or location ("sea") and the second character specifies the core type of actor or action ("robber"). Together, they create a new, intuitive meaning, a "sea robber", which is the literal sense of the English word "pirate". The formation is purely semantic, building the idea through the straightforward association of its two parts.