A person or thing that harrows; specifically, a farming implement for breaking up and smoothing soil, or metaphorically, something that causes distress.
From 'harrow' plus agent suffix -er. The agricultural sense is primary (a tool drawn by horses or oxen), while the emotional sense derives from the metaphorical use of the tool for distressing the mind.
A harrower is both a gardener's tool and an emotional weapon—the same word describes what you use to prepare a field and what you do when you disturb someone's peace. Ancient peoples understood that breaking up soil and breaking up souls used the same kind of force.
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