Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
This is esecially helpful if you want to take a call or listen to without having to constantly adjust the fit of your AirPods.
Source: https://www.devicemag.com/how-do-airpods-know-they-are-in-your-ear/