Is till a verb or adjective?

It may depend upon which 'till'you mean

1. To fight till death - preposition.

2. Till the time that - conjunction.....till and until are interchangable

3. To Till, as in labour by plowing - verb

4. A Till - is a drawer or a box or something in which money is kept - noun

5. As for adjectives - Words such as mill-tilled or well-tilled would be appropriate