Vale, Veil, Vail are homophones and consequently, easily confused words. The spell-check feature in word processing software would not catch a slip-up of these words. As long as it’s a word and that word is spelled correctly, spell-check moves on.
Vale is a noun meaning a valley or other tract of land.
Veil is a noun, that means a piece of cloth hung over the head and face. For the wearer’s safety, many veils are made with semi-transparent materials like lace, chiffon, tulle, or a nylon blend. Another design option for visibility is a slit or screen positioned in front of the eyes.
Vail is a verb, meaning to lower, or to let sink. It has archaic uses referring to gratuity, tipping one’s hat, and even as an alternative spelling for veil. It may be, though, that vail is outdated in every tense. In my reading, I see vail’s opposite (a.k.a. “antonym”), “avail”, used far more frequently. Avail is a verb that means to profit or benefit. It also has a noun form, meaning the benefit or the advantage to be gained by one party in a given situation.
The following sentence uses all four words correctly:
On a windy vale in Birr, the bride’s heels vailed into the peat beneath her; she struggled to keep her veil in place, to no avail.