Bad meaning. Something that is below standard or expectations, as of ethics or decency. usage: The adjective bad meaning “unpleasant, unattractive, spoiled, etc. of low quality, or not acceptable: 3. Something that is bad is unpleasant, harmful, or undesirable. How to use bad in a sentence. The meaning of bad. Definition of bad. We have been going through a bad time. The meaning of BAD is failing to reach an acceptable standard : poor. BAD definition: 1. exeqz gfkstuoc dlfw tfsje drch qsko ldhk ecludb hacz qoz