[nithinbekal]

Wouldn't that be too similar to NoMethodError? I recently came across the idiom in Smalltalk, where you would call subclassResponsibility:

    someMethod:
      self subclassResponsibility

I've suggested the name in the ruby bug tracker issue here:

https://bugs.ruby-lang.org/issues/18915

[yawboakye]

linguistically speaking, no method means the name isn’t even known, which isn’t the case here. the name exists and is known (after a successful declaration). what’s missing is the actual definition. if we lean heavily into language, perhaps only undefined method will do.