This expression means to work hard and continuously. It probably comes from the practice of knife grinders when sharpening blades to bend over the stone, or even to lie flat on their fronts, with their faces near the grindstone in order to hold the blades against the stone. All the early citations refer to 'holding' someone's nose to the grindstone as a form of punishment. This is in keeping with the notion of the continuous hard labour. The first known citation is from 1532.

Übersetzung:

sich dahinterklemmen

Gegenteil(e)

The opposite of "to hold/keep one's nose to the grindstone" is "to take it easy".

Synonym(e):

You could also say: to work hard and steadily.