noun
Mitsui O.S.K. Lines
A major Japanese shipping company; the name is a proper noun and does not have other common meanings.
商船三井は世界有数の海運会社です。
Mitsui O.S.K. Lines is one of the world's leading shipping companies.
The name combines 商船 (merchant ship) and 三井 (Mitsui, a major Japanese conglomerate). The exact historical derivation is a corporate naming decision.