a difficult or uncompromising person; a tough and insensitive person
He's a hard nut, all right.
The village of Sergy, just north of Grimpettes Wood, threatened to be a hard nut to crack.
“Not such a hard nut as you are, Jemmy,” said the man with a chuckle.
"That kind of fellow is a hard nut to crack," the Rector said consolingly.
The captain is a hard nut and the mates are both of the ‘bucko’ type.
"Oh, he's a hard nut to crack," said one of the officers who was sitting in the shadow at the other side of the fire.
That is a hard nut, in good sooth; too hard for you to crack.
He is a hard nut to crack, but he did himself proud this time.
Why can you crack a hard nut with a nutcracker when you cannot crack it by squeezing it between two pieces of iron?
When a man possesses that particular shape of muscle he is sure to be a hard nut to crack.
I invited him to come and visit me in Essex County, at the same time suggesting that I had a hard nut for him to crack.
A difficult or uncompromising person: was a hard nut, that's for sure (1888+)