The definition of ail is to feel sick or have pain.(verb)
An example of ail is for an older person to have poor health.
See ail in Webster's New World College Dictionary
Origin: ME eilen < OE eglian, to afflict with dread, trouble < egle, harmful; akin to Goth agls, infamous, ON agi > awe
See ail in American Heritage Dictionary 4
verb ailed, ail·ing, ails verb, intransitive
Origin: Middle English eilen
Origin: , from Old English eglian
Origin: , from egle, troublesome.
Learn more about ail