I love that kind of question, because when I came from Europe, where everything was measured in metric, to the US where things were measured in mystery measurements, I had to figure out how to use us recipes. This was before the net so it took a lot of research.
I agree with Mary, a tablespoon sounds right.

Yep, a tablespoon plopped ito the middle of whatever is just about right.
WG, yes, the measurements in the US were a mystery hard to comprehend, but one gets used to them. The ones I still have problems with: Fahrenheit vs Centigrade, the conversion is not easy and speeds/distance

I agree with the tablespoon, but for me it also depends of what. A dollop of sour cream and a dollop of whipped cream or icecream have different dimensions. The better it tastes, the bigger the dollop gets.

Like Lilo, I am still better with metric measurements, since they are ingrained and more accurate. My new stove I can can switch from Fahrenheit oven temps. to Centigrade, my kitchen scale has both weights and yardstick, measuring tape and ruler have both measurements - one side for my husband, one side for me.

I like the way the size of your dollop changes, anneliese :)

Jim, in man terms, think of a dollop as the amount of shaving cream you might put in your hand (if you use that).

I looked up the word and it was ambiguous. You folks being as smart as you are, I knew that you would/could make me smarter.

And, for the record, I don't shave. Last time was when Richard Nixon was re-elected to the White House. I was upset!

lol Jim. If you ever decide to shave with shaving cream, it sounds like you would need a r_e_a_l_l_y b_i_g d_o_l_l_o_p,
I wonder if the shaving cans have a dollop measure?

lilo, I also have trouble with " Fahrenheit vs Centigrade, the conversion is not easy and speeds/distance",
But the computer has taken care of that.

I've always referred to a dollop as a heaping tablespoon. Just using your regular soup spoon and scooping as much up as makes it round. Like scooping ice cream, but with a soup spoon.

If referring to whipped cream on pumpkin pie, I believe a dollop = 1 1/2 cups.

I think a dollop is intentionally ambiguous. The dolloper should add as much or as little as what they prefer. Agree Lynn, a dollop of ice cream will always be larger than a dollop of sour cream - even though I do like them both.