From Longman Dictionary of Contemporary Englishgrind somebody ↔ down phrasal verbCONTROLto treat someone in a cruel way for such a long time that they lose all courage and hope SYN oppress I’ve never let male colleagues grind me down. → grind→ See Verb table
Examples from the Corpus
grind down• Alternatively, chop the nuts very finely, add the garlic and use a pestle and mortar to grind them down.• I've never let male colleagues grind me down.• Larry moved her to Beaumont, Texas, where his jealousy and possessive ways slowly ground her down.• Westmoreland was wrong to count on his superior firepower to grind us down.• With Rufus it did to some extent come back again and all he could do was grind it down and soldier on.• The idea is to grind his victims down by boring them to death.• He grinds the stub down carefully and looks at it an instant reverentially.• I radioed for clearance and ground slowly down the runway.From Longman Business Dictionarygrind somebody → down phrasal verb [transitive] to spend a long time arguing with someone so that they are finally no longer able to oppose youHe’s a brilliant negotiator and eventually grinds down his opponents. → grind→ See Verb table 