India ink
US /ˈɪn.di.ə ɪŋk/
UK /ˈɪn.di.ə ɪŋk/

1.
a black ink consisting of lampblack or carbon black mixed with water to form a liquid or solid cake, used for drawing and printing
:
•
The artist used India ink for the detailed line work in his illustration.
•
She bought a bottle of India ink and a set of drawing pens.