37 definitions of GTO. Meaning of GTO. What does GTO stand for? GTO abbreviation. Define GTO at ev-kirche-jade.eu. In the poker world, we have adopted the term GTO to describe an optimal Generally, GTO (game theory optimal) means "most unexploitable". GTO may refer to: Music. GTO Records, a UK record label; GTO (band), an Australian band; The GTOs (Girls Together Outrageously), a late s "band".