It cannot be a particularly good dictionary if you cannot find "dismiss" in it.
Here is an online site that may be better:
http://www.onelook.com/dismiss =
•
verb 1 order or allow to leave; send away.
2 discharge from employment.
3 regard as unworthy of consideration.
4 Law refuse further hearing to (a case).
5 Cricket end the innings of (a batsman or side).
deferment =
–noun | 1. | the act of deferring or putting off; postponement. |
| 2. | a temporary exemption from induction into military service. |
There is no such word as "dimitter". Perhaps you meant "dismisser"?
Deferral is the same as deferment.