Definition of invisible ink in English:

invisible ink

noun

mass noun
  • A type of ink used to produce writing that cannot be seen until the paper is heated or otherwise treated.

    • ‘The case against Mr Azzam was based, in part, on allegations that he had invisible ink in his possession.’
    • ‘These include invisible inks and metal ‘nanoparticles,’ almost molecule-sized traces of metallic isotopes that can be detected with specialized equipment.’
    • ‘Residents were urged to use the pens, which write in invisible ink that can only be seen under ultra-violet light, and then pass them on to their next-door neighbour, and so on.’
    • ‘To thwart counterfeiters, tag your products with invisible inks or electronically readable devices that can verified by investigators or customs agents.’
    • ‘How do you tell when you run out of invisible ink?’
    • ‘One possible explanation is that invisible ink was used which wears off after only a few hours.’
    • ‘It has progressed from swallowing messages concealed in wax balls and using invisible inks, to methods that can be used on the internet today.’
    • ‘Visitors to the open day were able to try their hand at a series of techniques such as passport forgery, code-breaking and writing in invisible ink.’
    • ‘How do you tell when you're out of invisible ink?’
    • ‘But there is a line. It may seem to be drawn in invisible ink for a time, but eventually it will appear in dark colors, tinged with anger.’
    • ‘Ben is quick to deduce that the map to the treasure is inscribed in invisible ink of the back of the American Declaration of Independence.’
    • ‘He also had headed notepaper embossed with his code letter; he wrote on it in invisible ink, for all we know.’
    • ‘She had added this information to her notebook, together with directions for making invisible ink and a cordial water that would use up the glut of strawberries in the garden.’
    • ‘Peggy wrote in invisible ink, literally between the lines of innocent letters, she wrote the troop movements, the intelligence that the British were paying for.’
    • ‘Passing the rest of the inspection, our hands are stamped with invisible ink and we proceed through three thick steel gates.’
    • ‘Also popular was the practice of conveying information in invisible ink.’
    • ‘Republicans long ago realised that a secret deal with the British was not worth the invisible ink with which it was written.’
    • ‘The technology is being pioneered by winemakers in Australia and Italy, using holograms, invisible ink and unique numbers etched onto bottles.’
    • ‘One department dealt with the recognition of enemy forces, while others dealt with the dissemination of white overt propaganda and black covert propaganda, and with codes and the use of invisible inks.’
    • ‘The same bloody letter and on the back in invisible ink that only shows up under UV light is my signature.’