The noun "hair" can be both countable and uncountable.
Meaning: the mass of fibres on your head
Example sentence: I had lots of long, thick hair when I was young, but now I'm totally bald.
Meaning: a single strand of hair
Example sentence: She pulled a hair from her boyfriend's head and wound it around her finger.
Test your understanding:
- The police tested several of the hairs they found to see if the DNA matched.
- None of the strands of hair they tested matched the DNA.