look up

1.  Search for in a book or other source, as in I told her to look up the word in the dictionary. [Late 1600s]
2.  Call on or visit, as in I'm going to look up my friend in Chicago. [Mid-1800s]
3.  Become better, improve, as in Business is finally looking up. [c. 1800]
4.  look up to. Admire, respect, as in The students really looked up to Mr. Jones. [Early 1700s]

Definition: improve
Antonyms: decline, worsen

v

Definition: research
Antonyms: wing it

The verb has one meaning:

Meaning #1: seek information from
  Synonyms: consult, refer