from Wiktionary, Creative Commons Attribution/Share-Alike License
- adv. In an authoritative manner, being worthy of trust.
from The Century Dictionary and Cyclopedia
- In an authoritative manner.
- With due authority.
- With a show of authority.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adv. in an authoritative and magisterial manner
authoritative + -ly (Wiktionary)