Originally Posted by
casablanca
Boeing QRH has term nearest suitable airport which doesn't seem to imply a time.
In case of time critical items like smoke/fire they also use terminology "earliest"/ and 'Immediate" which implies immediate diversion to a runway or in a severe situation flight crew should consider over-weight landing, tailwind landing, or even ditching. This is in the checklist instructions -non normal checklist
See the FAA definition and Boeing fctm for “nearest suitable “ meaning nearest in time in aviation terms that is . Immediate implies something else I.e ASAP