plural of rat
"The farmers found that rats had infested their grain storage silos."
Third-person singular simple present indicative form of rat
"The mouse squeaks when he rats to his mother about losing his toy."
In plain English: To rat means to tell on someone else by giving their secrets away to an authority figure.
"We should cut our losses and rats now before things get worse."
Expression of annoyance or disgust; damn, darn.
"Rats! I forgot to lock the front door again."