IPA: /ˈɛəˌwɜːðɪnəs/
KK: /ˈɛrˌwɜrðɪnəs/
The condition of an aircraft being safe and suitable for flying.
The aircraft was grounded due to a lack of airworthiness certification.
Airworthiness is formed from "air" (meaning the invisible mixture of gases surrounding the Earth) and "worthiness" (from Old English "wyrðnes" meaning worth or value). The term describes the quality of an aircraft being fit or safe for flight in the air.
Think of 'air' as the space where planes fly and 'worthiness' as being fit or valuable — together, they mean that an aircraft is fit for flying.