beatenest n [beatenest adj]
One’s best; one’s utmost effort.
1889 Perry Chief (IA) 13 Dec [6]/1 (newspaperarchive.com), I reckon I did my beatenest to put myself on a level with my new associate. 1907 Wright Shepherd 12 Ozarks, ’Taint no wonder ’t all, God rested when he made these here hills; he jes naturally had t’ quit, fer he done his beatenest an’ was plumb gin [=given] out. 1912 Charleroi Mail (PA) 16 Feb 1/4, Consequently Fogarty and his men will play their beatenest to ward off a Cherub victory.