dose

Borrowed from Middle French dose, from Late Latin dosis, from Ancient Greek δόσις (dósis, 'a portion prescribed'), literally 'a giving,' from δίδωμι (dídōmi, 'to give'). Greek physicians like Galen used it to mean a measured amount of medicine.

The word passed from Greek medical vocabulary through Late Latin and Middle French into English, keeping its core sense of a prescribed amount of medicine, and it mostly displaced the older English word drench for this meaning.

It's a doublet of the word doos, meaning the two share the same ultimate root despite arriving in English by different paths.