It depends.
You might imagine situations in which you would need to add oil to a mechanism in drops. In such a situation you would not add 3.24 drops, you would add, say, 4 or 5 drops. In these situations the amount of oil would be discrete.
On the other hand, the measure of the oil in a tank could be given to some considerable degree of precision. It would not be counted. In this case the amount of oil would be (effectively) continuous.
ocean depth is a continuous or discrete variable?
It is a continuous variable.
discrete
It is a continuous variable.
Date is a discrete variable whereas date/time would be continuous.
It is a continuous variable.
continuous discrete
No, Patient's gender is not a continuous variable. It is discrete variable.
It is discrete even though time itself is continuous.
Absorbance is considered a continuous variable.
No, it is a continuous variable.
No, it is a continuous variable.