1. [n]  aromatic bulb used as seasoning
2. [v]  cause bodily suffering to
3. [v]  be unwell, ill, or ill disposed

AIL is a 3 letter word that starts with A.

1. \Ail\ ([=a]l), v. t. [imp. & p. p. {Ailed} ([=a]ld); p. pr.
   & vb. n. {Ailing}.] [OE. eilen, ailen, AS. eglan to trouble,
   pain; akin to Goth. us-agljan to distress, agls troublesome,
   irksome, aglo, aglitha, pain, and prob. to E. awe. [root]3.]
   To affect with pain or uneasiness, either physical or mental;
   to trouble; to be the matter with; -- used to express some
   uneasiness or affection, whose cause is unknown; as, what
   ails the man? I know not what ails him.
         What aileth thee, Hagar?                 --Gen. xxi.
                                                  17.
   Note: It is never used to express a specific disease. We do
         not say, a fever ails him; but, something ails him.
   

2. \Ail\, v. i.
   To be affected with pain or uneasiness of any sort; to be ill
   or indisposed or in trouble.
         When he ails ever so little . . . he is so peevish.
                                                  --Richardson.
   

3. \Ail\, n.
   Indisposition or morbid affection.             --Pope.