'maritimely' originates from English, specifically formed from the adjective 'maritime' + the adverbial suffix '-ly'. 'maritime' ultimately comes from Latin 'maritimus', where 'mare' meant 'sea'.

'maritime' changed from Latin 'maritimus' (from 'mare' meaning 'sea') through Old French/Medieval Latin into Middle English 'maritime', and the modern English adverb 'maritimely' was formed by adding the suffix '-ly' to create an adverbial form.

Initially, the root (from Latin) meant 'of or belonging to the sea'; over time this became the English adjective 'maritime' meaning 'relating to the sea or shipping', and 'maritimely' came to mean 'in a maritime manner' (adverbial use).