vi·ral 
(vīrəl)
(vīrəl)adj.
1. Of, relating to, or caused by a virus.
2. Of or relating to the rapid propagation of information, ideas, or trends by means of social networks rather than conventional mass media: viral marketing.
viral·ly adv.
- black sheep
- Black Shirt
- Blackshirt
- black skimmer
- blacksmith
- blacksmithing
- black smoker
- blacksnake
- black spot
- black spruce
- Blackstone
- blackstrap
- blacktail deer
- black-tailed deer
- black tea
- blackthorn
- black tie
- black-tie
- blacktop
- Black Volta
- black vomit
- black vulture
- black walnut
- Black Warrior River
- blackwash