Definition of "alack"

alack

/əˈlæk/

interjection
1. An expression of sorrow or mourning.
  Quotations
  On a day, alack the day: / Loue, whoſe Month is euery May, / Spied a bloſſome paſſing faire, / Playing in the wanton ayre:
  c. 1595–1596 (date written), William Shakespeare, “Loues Labour’s Lost”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act IV, scene iii], page 133
  Alack, would that Edward listened more to me and less to the queen’s kith! These Woodvilles!
  1843, Edward Bulwer[-]Lytton, The Last of the Barons, London; New York, N.Y.: George Routledge and Sons […]