Significat

1. to be able to; can, to know how (to have the ability or knowledge to do something) [+infinitive = to do what]
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) [+infinitive = to do what]
5. (obsolete) to know (to perceive the truth or factuality of; to be certain of or that)