May dew

the morning dew of the first day of May, to which magical properties were attributed.

See also: May

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
Not to be outdone Miracle May Dew "gaspers", as they were no doubt called, offered a dewy-eyed maiden in languorous pose.
When I saw my neighbour face down in the grass I thought she had been on the sherry but no, she still believes the old wives tale that the May Dew helps you look young.
Girls bathed their faces in May dew to ensure a lovely complexion, made garlands of flowers, and paraded with branches of hawthorn in full bloom.
Roy Christian, author of Old English Customs, complains, "May Day in England is not what it used to be." It's hard nowadays to find a maiden who rises early on May Day morn to wash her face with May dew and so acquire a beautiful complexion.