rad-scrape

This root is all about the same gritty action: dragging something hard across a surface to wear it away. It comes from Latin rādere, "to scrape, scratch, shave," with the past participle rāsus (which is why some words keep -d and others -s).

Start with the gentlest version. A razor is simply "the scraping tool" — rad + -or — the everyday blade that scrapes hair off skin. Hold that image of metal dragging across a surface, because the whole family is variations on it.

Add the prefix ab- (away) and you get the "scraping away" branch:

- abrade — to wear a surface down by rubbing or scraping it.
- abrasion — the result: a worn patch, or a scrape on the skin (you get an abrasion when you fall on rough ground).
- abrasive — describing something that scrapes: sandpaper is abrasive. Then a wonderful metaphor: a person can be abrasive too — someone whose manner rubs you the wrong way, grating like rough material against skin.

Finally, the action turns total. raze (note the s-spelling, from rāsus) means to scrape a building all the way down — to demolish it to the ground. It's the same scraping motion taken to its extreme: not just wearing a surface, but erasing the whole thing.

Watch out for two look-alikes that are not in this family. Raise (to lift up) sounds exactly like raze but means the opposite — one builds up, the other tears down. And erase is a genuine cousin (e- + rad/ras, "to scrape out"), but radical, radio, and radius come from a different Latin root, radix/radius (root/ray), and have nothing to do with scraping.

The thread is consistent and physical: from a razor's light shave, to an abrasion's rough scrape, to razing a city flat — it's always something hard dragged across something else.