'grader' originates from English, specifically formed from the noun 'grade' plus the agentive suffix '-er' (meaning 'one who does').

'grade' entered English from Old French/Anglo-French (Middle English) and ultimately from Italian 'grado' and Latin 'gradus' meaning 'step'; the agentive '-er' is a native English suffix used to form nouns meaning 'one who ...', producing 'grader'.

Initially related to 'step' or 'rank' (from Latin 'gradus'), the sense evolved to mean 'degree' or 'quality' and later 'to assign a rank or score'; 'grader' developed as 'one who assigns grades' and by extension to name machines that level or sort.