bettermost adj, n Also bettermost best Pronc-sp bettermos’ [Brit dial and colloq; OED3 1737→, EDD ] esp NEast obs Cf bestmost n

Best, greatest; the best that one can do, one’s best clothing.

1824 Sigourney Sketch CT 111, She takes in weavin’, . . and so buys herself her bettermost cloes, which is a help to me. 1847 Graham’s Mag. 30.246 sePA, Mr. Kerr Mudgeon . . all ready except the final operation of putting on his bettermost coat—has torn that important article of gentlemanly costume. 1851 Hawthorne House 7 Gables 182 neMA, So Hepzibah and her brother made themselves ready, . . in their faded bettermost, to go to church. 1855 Simms Forayers 113 SC (as of 1780s), The bettermost part b’longed to Miss Carrie here. 1859 (1968) Bartlett Americanisms 30, Sometimes is heard the expression bettermost best; as, “These girls are dressed in their bettermost best. 1867 Galaxy 3.447, Let him do his best to inspire us; and let him above all do his bettermost to deal with us in a perfectly fair spirit. 1895 Boston Post (MA) 21 May 4/3, The deacon favors a crow, especially when he’s goin’ to meetin’ in his Sunday bettermost. 1898 Scott Mobilians 99 AL [Black], I says to Peter Downs . . dat it would bin bettermos’ fur him to do like his name-sake, de great desciple. 1905 DN 3.3 cCT, Bettermost. . . Best. 1922 Trenton Eve. Times (NJ) 16 May 7/5, [Advt:] These are capes that you will be pleased enough with for bettermost best wear.