What it means
The dull, thankless, labour-heavy part of any job, the bits that take effort and patience but bring no glory. The grunt is the lowly foot soldier who does as told without complaint, and grunt work is what lands on his plate. Necessary, unglamorous and rarely noticed until it is not done.
Usage examples
"Behind every slick launch there are weeks of grunt work, testing, fixing typos and chasing approvals nobody ever sees."
"The interns did all the grunt work while the partners took the credit."
"Setting up the venue is pure grunt work, but someone has to do it."
"We can't get to the fun bit yet, we've still got all the grunt work to chew through first."
"Everyone loves the big presentation, nobody wants the grunt work that kept the whole thing from falling on its face."
Where it comes from
It comes from US military slang, where a grunt was an infantry soldier, especially the low-ranking one doing the rough, dirty, repetitive jobs. By the mid 20th century, that sense spilled into civilian life, and grunt work came to mean the boring heavy-lift part of any task that has to get done but wins zero applause.
