I know that "not bigger" in (1) is used to state a fact: Hummingbird eggs are either the same size as or smaller than, coffee beans. I also know that "no bigger" in (2) is used to deny that hummingbird eggs are bigger than coffee beans or to express your surprise.
(1) Hummingbird eggs are not bigger than coffee beans.
(2) Hummingbird eggs are no bigger than coffee beans.
One of the things that I'm not sure of for (2) is what you really mean by "surprise."
My understanding is that there is no significant difference in size between hummingbird eggs and coffee beans, so you are surprised at how small hummingbird eggs are.
In short, I had understood (2) meant (3a) but not (3b).
(3) a. Hummingbird eggs are as small as coffee beans.
b. Hummingbird eggs are either the same size or smaller than, coffee beans.
My question is,
Do you think (2) actually means (3b) when you use "no bigger" to mean surprise?
Thank you in advance
Seiichi MYOGA

