INK

noun

1. A pigment (or dye)-based fluid used for writing, printing etc.
2. A particular type, color or container of this fluid.
3. The black or dark-colored fluid ejected by squid, octopus etc, as a protective strategy.

verb

1. To apply ink to; to cover or smear with ink.
2. To sign (a contract or similar document).
3. To apply a tattoo to (someone).