up to

1. Occupied with, engaged in, as in What have you been up to lately? This usage can mean “devising” or “scheming,” as in We knew those two were up to something . It also appears in up to no good , meaning “occupied with or devising something harmful,” as in I'm sure those kids are up to no good . [First half of 1800s]

2. As far as or approaching a certain point. For example, The water was nearly up to the windowsill , or They allowed us up to two hours to finish the test , or This seed should yield up to 300 bushels per acre . [c. a.d. 950]

3. Dependent on, as in The success of this project is up to us . [c. 1900] Also see the following idioms beginning with up to .

4. be up to . Be able to do or deal with, as in When I got home, she asked if I was up to a walk on the beach . This usage is often put negatively, that is, not be up to something , as in He's not up to a long drive . [Late 1700s]