Q. I have a recipe that calls for "4 cl. thick cream". What is a "cl."?
A centiliter is one-hundredth of a liter, and a liter is the metric measure that is slightly less than 1 quart in the US system of measurement. Recipes that use metric measures more often use the smaller unit, milliliters, or one-thousandths of a liter, to denote volume. In that case, your recipe would have called for 40 ml.
In either event, 4 cl is between 1/8 and 1/4 cup if you can keep count accurately (and we often cannot), it is 8 teaspoons.