* -ness: This suffix can be used to form nouns indicating a state or condition. For example, "busyness" means the state of being busy.
* -ly: This suffix can be used to form adverbs indicating a manner or way of doing something. For example, "busily" means in a busy manner.
You could also use other suffixes like -ed (to form the past participle of "busy" which is "busied") or -ing (to form the present participle which is "busying") to create related words. However, these words don't necessarily convey the same meaning as "busy" itself.