'Baltimorean' originates from English, specifically the word 'Baltimore' with the adjectival/demonymic suffix '-an' (from Latin '-ānus' via Old French), where the suffix '-an' meant 'pertaining to or connected with'.

'Baltimore' itself ultimately comes from the Irish place-name 'Baile an Tí Mhóir' (modern Irish), meaning 'town of the big house'; the name passed into English as 'Baltimore' and was later used to form the demonym 'Baltimorean' by adding the suffix '-an'. The American city of Baltimore was named after the title 'Baron Baltimore.'

Initially the elements referred to the Irish place-name meaning 'town of the big house,' and over time the English place-name 'Baltimore' gave rise to the demonym meaning 'a person from or relating to Baltimore,' which remains the current meaning.