A harrow is a frame of spikes dragged over ploughed soil to break it up. Drag the harrow, a spring-tine harrow, harrow the field.
The plough turns the soil over in great clods and the harrow breaks them down into a seedbed, so the two go in that order. To be harrowed is to be deeply distressed, and harrowing comes from exactly that image of being raked over.
1nounharrowA frame of spikes dragged over ploughed soil to break it up.
“The tractor pulled a harrow over the field, leaving the soil fine and ready for seed.”
harrow is a tool.
Middle English harwe, from a Germanic or Norse word for the implement.
Old Norse
harfr
Old English
*hearwa
Middle English
harwe
English, today
harrow
From Middle English harwe, harow, from Old English hearwa (perhaps ultimately cognate with harvest), or from Old Norse harfr/herfi; compare Danish harve (“harrow”), Dutch hark (“rake”). Akin to Latin carpo. According to the OED, the verb senses are partly derived from the noun sense, partly from a by-form of the verb harry, itself from Old English hergian.
Etymology from Wiktionary, CC BY-SA