1.VerbUsed other than figuratively or idiomatically: see look, up.
"We stayed up late to look up at the stars."
2.VerbTo have better prospects.
"Things started looking up after Jim moved back in with his parents."
3.VerbTo obtain, or seek to obtain, information about something.
To obtain information about something from a reference book.
"I didn't know what a mitochondrion was until I looked it up in a dictionary.; If you look up a bunch of random characters, there will probably be no results."
4.VerbTo obtain information about something from a reference book.
"I didn't know what a mitochondrion was until I looked it up in a dictionary."
5.VerbTo enter a query into a database or search engine.
"If you look up a bunch of random characters, there will probably be no results."
6.VerbTo reconnect or meet with someone that one used to know.