My Dutch vocab book says het ons is 100 grams. In the US at least, an ounce is (roughly) 30 grams.

Is my textbook comically wrong, or do the Dutch and the USians define an ounce very differently?

mx @pixiesnoot, that is the correct definition. an ons is used to mean exactly 100 g (and a pond is exactly 500 g). this is one of the last remnants of the original introduction of the metric system in 1820, where all the familiar measures were rounded to metric values. gradually most traditional measures fell out of use but ons/pond remained. https://nl.wikipedia.org/wiki/Nederlands_metriek_stelsel

@1 @pixiesnoot in general the pre-metric units were quite different in size

depending on where and when you were in what is now germany a mile could have been between anywhere from 1km to 10km

@1 @pixiesnoot germany was like probably the prime raccandidate for units unification because like

you walked a city over and they had raccompletely different units

napoleon fixed this a little bit but not on purpose