What is the meaning of the word "busy"?

Definitions:

(of facilities such as telephones or lavatories) unavailable for use by anyone else or indicating unavailability adjective
- (`engaged' is a British term for a busy telephone line)
actively or fully engaged or occupied adjective
- They kept busy with their work.
crowded with or characterized by much activity adjective
- a very busy week
overcrowded or cluttered with detail adjective
- a busy painting
to keep busy with verb
- I busied my children with the coloring books.