WordNet sense 1 (an insignificant student who is ridiculed as being affected or studying excessively):

dweeb, nerd, wonk, swot

WordNet sense 2 (work hard):

dig, drudge, labor, moil, toil, travail, labour

WordNet sense 3 (press or grind with a crunching noise):

crunch, cranch, craunch

WordNet sense 4 (make a grating or grinding sound by rubbing together):

grate

WordNet sense 5 (hard monotonous routine work):

drudgery, plodding, donkeywork

WordNet sense 6 (the act of grinding to a powder or dust):

mill, pulverization, pulverisation

WordNet sense 7 (reduce to small pieces or particles by pounding or abrading):

bray, comminute, mash