Amain, a plain, a canail… wait a minute. That’s not how it goes.
amain adv. IPA Pronunciation: 
at full force or speed
MESSENGER
His soldiers spying his undaunted spirit
A Talbot! a Talbot! cried out amain
And rush’d into the bowels of the battle.
– Henry VI, Part 1 (I.i)
There’s a certain economy about this word. I can easily hear it in a command, which it is used as most often. You’ll mostly find this in the Henry VI series. 8 out of 13 times it is used by Shakespeare are in one of the Henry VI plays. Wowzers.