As a non-native English speaker I sometimes struggle with those words added after verbs: off, on, up, down, etc.

What words come from Celtic languages? I thought it was all Germanic with Latin and French words being borrowed later.

As a French-speaker, it has always been my instinctual understanding from seeing the word and knowing how English has taken words from Latin and French.

English-speakers are really unlucky to have one of the most ambiguous word for situations where the need for clarity is of such great importance, especially as it concerns safety, even saving lives.