- indelible ink used for marking linen, clothes, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Examples from the Web for marking ink
Because on the other days you forgot to bring home the marking-ink.
I have my own business to attend to in the city without always thinking about marking-ink.