{adj. phr.} 1. In union or harmony; in agreement or sympathy. Not usually used informally. * /He felt at one with all the poets who have sung of love./ 2. Of the same opinion, in agreement. * /Husband and wife were at one on everything but money./ Contrast: AT ODDS.
AT ONE
Meaning of AT ONE in English
Slang English vocab. Английский сленговый словарь. 2012