Synonym for busy/occupied that's something like "predisposed" or "undeposed"

There’s a word that means "busy" that is similar to "predisposed" or "undeposed" – and now I can’t remember it at all. An example usage would be "I’m going to be till next Monday, so I can’t make it."

I tried looking up synonyms but couldn’t find it. It’s possible that it doesn’t exactly mean "busy" and that I attributed that meaning to it from context, but I’m still unable to figure out what the word could be.