Εννοια

1. to be able to; can, to know how (to have the ability or knowledge to do something)
2. to know (to be able to recite from memory)
3. to know (having learned, to be able to apply, e.g. a language)
4. to be able to; can, to know how (to do better than others)
5. (obsolete) to know (to perceive the truth or factuality of; to be certain of or that)