Watering Hole Attack
In a watering hole attack, the attacker compromises a site likely to be visited by a particular target group, rather than attacking the target group directly.
Source: NIST CNSSI 4009-2015
A security exploit where the attacker infects websites that are frequently visited by members of the group being attacked, with a goal of infecting a computer used by one of the targeted group when they visit the infected website.
Source: NIST NIST SP 800-150 under Watering Hole Attack