- The definition of clueless is someone who doesn't know or understand something or is ignorant about a situation.
Someone who thinks their computer is broken when really it's just not plugged in is an example of clueless.
- lacking clues or information
- stupid; obtuse
- ignorant or uninformed, specif. regarding a certain situation or matter: clueless about baseball
Lacking understanding or knowledge.
(comparative more clueless, superlative most clueless)