big cities are cool to look at. big cities do not have a lot of trees.
etc
A mouse is not as big as an elephant.
I am apprehensive on going to Big Bear!
there was a big tidal wave
"I made a big mistake", he said ruefully.
a conflagration is a big fire
the big quiet classroom was freakishly awkward
The rivulets along the big lake
I think that the stage in our school is very big
my dvd player is so big that it is not portable.
The whale looked really BIG compared to the little girl. that's how
If something is gigantic, it is large. For example, a sentence using the word would be "The monster is absolutely gigantic." It means large, as well as big.
There was a big bang and I turned around to see smoke and flames coming out of my television!