Would you use “grumpy” as a synonym for “irate”?
No, grumpyness is a chronic state of being easily irritated and generally feeling cross, whilst being irate is an acute emotion caused by some immediate factor. Irate also seems stronger to me.
No. Irate is much stronger than grumpy, for one thing. If I was describing myself as irate, I’d be very angry, usually towards a specific action/event. I’m not just going to start feeling irate for no good reason.
Being grumpy is just being irritable and easily annoyed, and doesn’t necessarily have to be related to an event. People can sometimes just wake up grumpy and not really know why.
“Grumpy” does not mean “angry”.
No. We call our daughter L “Grumpystiltskins” when she is pouting. “Irate” seems far too strong a description for average 10-year-old sulking.
Is this crossword puzzle-related?
Joe
No.
Grumpy is to irate as pleased is to ecstatic.
How about “apoplectic”?
Good guess, but no. I’m proofing some curricular materials for HS students who have problems with reading, and there’s a list of words from the reading (A Separate Peace) that said students may need help with. The word is “irate,” and they’re suggesting “grumpy” as a synonym. My reaction – and I’m delighted at the unanimity with which y’all share it – is “WTF.”
And this probably would create more problems than it would solve, in this situation (see above). 
Nope. If I’m irate, it’s about a particular thing/situation/person. If I’m grumpy, it’s just a general feeling of being easily annoyed at anything and everything.
No. Grumpy is quiet and you would never know when I was grumpy. Irate has noise and trust me that you will indeed know if I am ever irate.
Grumpy is someone who’s had too little sleep, too little coffee and has a long day ahead of them. Irate is that same person when they find that their inconsiderate roommate has used the last of the coffee, left the bread open to go stale and still hasn’t left their share of the phone bill.
I guess you can’t substitute in ‘pissed’ for ‘grumpy’ 'cus that seems like it would be a lot easier for HS students with reading difficulty to understand.
That is a weird choice. It seems like “angry” would be the more obvious synonym.
Grumpy is what I feel when I get 5 hours of sleep and someone bothers me with an inane question. Grumpy is what I feel when I have to go to the theater instead of playing video games because The GF is making me.
Irate is what I felt when someone stole my GPS out of my car. Irate would be if The GF was sleeping with the pool boy.
We must find the one person who voted yes and mock him or her soundly, followed by a spanking, and then the oral sex!
No. I hear a lot of irate callers in a normal day at work. I don’t hear any grumpy ones.
I am apparently only the second person to say vote yes. I have never known about any difference between the two words. Context can slightly make one of them more appropriate than the other, but as is normal in English, both will pretty much always work when substituting one in for the other.
Maybe they were thinking about irascible?