A person or device that uses a file (the tool) to smooth or shape surfaces, or someone who files documents away for storage.
From 'file' (Old English 'feol') + '-er' (Old English agent suffix meaning 'one who does'). The word can refer to either tool-users or document organizers.
A filer could be a craftsperson making metal smooth, a secretary organizing paperwork, or even a digital system sorting your photos—the same word works for wildly different jobs because the core action is the same!
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