Math means good, so gu math in this context must mean, "It is good and wet?"
'Well wet' literally, so essentially, aye. One of the idiomatic uses of 'well' in Gaelic is as a modifier, much like 'very' and 'rather'. Some English speakers use it in much the same way - "she's well fit!" ;)
gu math means really.
And in the sentence Tha mi gu math or Tha gu math, it means well: I am well.
No, it means 'well', it's a perfectly standard adverbial phrase from an adjective. 'Gu' plus adjective equals adverb.
Why is "gu mòr" wrong?
Can you please tell me why "Tha i glè fhliuch" is wrong? Tapadh leat!