(n.) a thick summer sea mist
A water-aynd, or eynd, is a thick sea mist that drifts far inland from the coast during the summer months. Literally, it means ‘water-breath’.
Aynd comes from anda, a largely long-lost Old English word for a breath or a single exhalation from the lungs. Breath itself—derived from another Old English word, bræð, that could also be used of smells, vapours and odours as well as bodily exhalations—has largely replaced it in standard English today. But anda apparently clings on to existence in this one expression taken from the dialects of eastern and North Sea England (and East Anglia) in particular.
Old English anda also morphed into another word, ond or onde, that came to be used of a person’s spirit or innate being, or for any particularly strong feeling or emotion. Alas, it too appears not to have stood the test of time, and largely fell out of use in the 1500s.