
Off colour
Subtle Discomfort
Used when someone isn't very sick, but doesn't feel 100% well. It's subtle, not severe.
I think I'll skip the gym today—I'm a bit off colour.
Not Depressed
Doesn't mean very sad or depressed, but having a slightly low mood.
Sorry for the low energy today, I'm feeling off colour.
Temporary State
Implies a temporary condition, not a long-term feeling or illness.
I've been a bit off colour since yesterday, but I should be fine by tomorrow.