She threw a sharp, sideways glance at Dumbledore.

[diamondcutter]

"I know that," said Professor McGonagall irritably. "But that's no reason to lose our heads. People are being downright careless, out on the streets in broad daylight, not even dressed in Muggle clothes, swapping rumors."
She threw a sharp, sideways glance at Dumbledore here, as though hoping he was going to tell her something, but he didn't, so she went on.
Source: Harry Potter and the Sorcerer's Stone, J. K. Rowling

What do you think the word “sharp” means here? Critical or severe?

 

[Skrej]

Neither in this context. See definition 6b. Note how she was looking at someone else, then suddenly ('threw') looked sideways at someone else (Dumbledore).