1. In computer thinking, a mental glitch or a brief interruption of the mental process: While Sam was developing a new computer program, he let his mind wander and it resulted in a thinko so he had to correct the error.
2. A careless mistake made when considering something which is often referred to as a blooper or blunder: As the proofreader for the publishing firm, it was Alice’s job to check for thinkos in the preliminary or rough copies.