1. without colour; having no colour or hue
2. lacking interest, liveliness, or distinctive character; dull

Examples

• The liquid in the beaker was colourless and odourless.
• His colourless prose made the novel difficult to enjoy.
• A colourless gas escaped from the container.
• She gave a colourless performance that failed to impress the audience.
• The walls were painted in a colourless shade of grey.
• His colourless personality made him forgettable at parties.