Family History and Genealogy Resources by Surname
Slack Surname Origin
(Locality). A valley, or small shallow dell.
Source: An Etymological Dictionary of Family and Christian Names With an Essay on their Derivation and Import; Arthur, William, M.A.; New York, NY: Sheldon, Blake, Bleeker & CO., 1857.
Slack Surname Meaning and Family Facts
There is more to Slack family history than the origin of your surname:
A Slack Family History Thought:
'Those who forget their past are destined to repeat it.' --Robert A. Heinlein