Give up and Knuckle down

Give up verb - To give (something) over to the control or possession of another usually under duress.

Knuckle down and give up are semantically related. In some cases you can use "Knuckle down" instead a verb "Give up".

Knuckle down verb - Work very hard, like a slave.

Give up and knuckle down are semantically related. Sometimes you can use "Give up" instead a verb "Knuckle down".