The purpose of this paper is to discuss the description of multi-word expressions (MWEs) in maritime English dictionaries from a cognitive perspective. Japan relies on maritime transport for over 90% of its imports and exports. However, the educational materials used in institutions training maritime personnel for these international routes, particularly dictionaries, feature descriptions reminiscent of simple English word lists. This approach is intended for bringing dictionaries into the National Maritime Officer Examination to answer English questions, falling far short of content suitable for long-term learning plans. While dictionaries face space constraints, they must still meet usability needs. The research methodology involves listing entries from existing maritime English dictionaries and examining previous studies on MWEs descriptions. In addition, following the presentation of examples from learners' English-Japanese dictionaries, this paper proposes dictionary headwords incorporating multi-word expressions (MWEs). The descriptions include maritime English, based on the utilization of corpus data and the theoretical framework of metaphor, metonymy, and metonymy in cognitive linguistics. The main finding demonstrates that the cognitive perspective of maritime English blurs the semantic boundaries with general English. This provides an important point for discussion in vocabulary learning.