Gainsay

gainsay \gayn-SAY; GAYN-say\, transitive verb:
1. To deny or dispute; to declare false or invalid.
2. To oppose; to contradict.

"The evidence was clear; there was no way that the family could not possibly gainsay their presence at the scene of the crime."

Someone who gainsays is called a gainsayer.

Gainsay, you will; gainsay, you won't..

Aegis

aegis \EE-jis\, noun:
1. Protection; support.
2. Sponsorship; patronage.
3. Guidance, direction, or control.
4. A shield or protective armor; -- applied in mythology to the shield of Zeus.

Also spelt egis.

"We were highly honoured to be under the aegis of Emperor Caesar which afforded us easy passage across the Empire."

There is a great article on Wikipedia which describes the mythological associations that the word aegis has. Apparently it is the sheild or buckler of Zeus.

Aegis is also a variant of UNIX which was used on Apollo workstations. (Yes, that is true, but hey, I'm a geek)

It is also the name for a network authentication system from Meetinghouse Datahouse Communications popular in 802.1x networks. (Yep, big geek)

Another geeky definition is that AEGIS is a CASE tool (I remember those :)) for project change management. (It's ok, I do wash behind my ears).

One, two aegis my shoe!