'moralizer' originates as an English agent-noun formation from the verb 'moralize', which itself comes from French 'moraliser' and ultimately from Latin 'moralis', where 'mos/moris' meant 'custom'.

'moralizer' developed by adding the agent suffix '-er' to the verb 'moralize'; 'moralize' entered English in the mid-16th century from French 'moraliser', derived from Latin 'moralis'.

Initially related to making or treating something as moral (from 'moralize'), the word's usage broadened to refer specifically to a person who lectures or judges others on moral grounds ('moralizer').