Something that is colourless has no colour at all.
a colourless, almost odourless liquid.
一种无色的、几乎无味的液体。
If someone's face is colourless, it is very pale, usually because they are frightened, shocked, or ill.
Her face was colourless, and she was shaking.
她脸色苍白,全身发抖。
Colourless people or places are dull and uninteresting.
the much more experienced but colourless general.
这位经验更为丰富但平淡无趣的将军。