Definition of tar spot
1a
: a leaf-blotch disease of maple, willow, or oak caused by fungi of the genus Rhytisma that produces raised black stromatic cushions on the foliage
b
: one of the spots produced
2
: a disease of many grasses caused by a fungus (Phyllacora graminis) and resembling the tar spot of trees
Test Your Vocabulary
The Great British Vocabulary Quiz
-
- Named after Sir Robert Peel, what are British police called?

Test your knowledge - and maybe learn something along the way.
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Share tar spot