1. to schedule something (Mainly for meetings. Sounds formal, so DON'T use it for casual meet ups.)
Opposite (closest): absetzen
2. to set, to estimate, to assume (Set a certain amount when you don't know 100%. Think of trying to analyze a company and setting a number as estimated earnings. Sounds technical, and mostly used in finance.)
3. to put on weight (Usually in combination with "weight" or "fat".)
4. to get ready, to be about to ("ansetzen zu" - The moment when you get ready to start doing something. Primarily used in contexts of speaking and singing and also for basical physical movements. Oh, and also for plane attempting to land.)
5. to prepare (In cooking when you prepare something that then has to sit for a while. Like a broth or some herbal liquor or something. NOT for dough, though.)
6. to start, to apply (In the context of having a starting point for a bigger, complex problem or task.)
