Conversation so far:
What is nominal GDP?
Nominal GDP is GDP evaluated at current market prices. Therefore, nominal GDP will include all of the changes in market prices that have occurred during the current year due to inflation or deflation.
Why is nominal GDP not a good measure?
The problem comes when you're comparing GDP across different time periods. Nominal GDP includes “growth” in the value of output due to inflation as well as production
What is the between nominal and real GDP?
Nominal GDP is the sum-total of the economic output produced in a year valued at the current market price. Real GDP is the sum-total of the economic output produced in a year values at a pre-determined base market price.

Question: How is it related to gross national income
Self-contained rewrite: How is nominal GDP related to gross national income?