v. phr. , informal 1. To attack or fight with great strength or energy; have a bad argument. Bill slapped George's face and now they're going at it hammer and tongs in back of the house. Helen and Mary have been arguing all day, and now they are going at it hammer and tongs again. 2. To start or do something with much strength, energy, or enthusiasm. The farmer had to chop down a tree and he went at it hammer and tongs. Charles had a lot of homework to do and he went at it hammer and tongs till bedtime.
Compare: IN EARNEST, WITH MIGHT AND MAIN.