2. Adverb. (archaic) Into a state of harmony, friendship or reconciliation. ¹
3. Adverb. In agreement, unanimous, of the same opinion. ¹
¹ Source: wiktionary.com
Medical Definition of At one
1. 1. In concord or friendship; in agreement (with each other); as, to be, bring, make, or set, at one, i. E, to be or bring in or to a state of agreement or reconciliation. "If gentil men, or othere of hir contree Were wrothe, she wolde bringen hem atoon." (Chaucer) 2. Of the same opinion; agreed; as, on these points we are at one. 3. Together. "He and Aufidius can no more atone Than violentest contrariety." (Shak) 2. To stand as an equivalent; to make reparation, compensation, or amends, for an offense or a crime. "The murderer fell, and blood atoned for blood." (Pope) "The ministry not atoning for their former conduct by any wise or popular measure." (Junius) Origin: OE. At on, atone, atoon, attone. Source: Websters Dictionary (01 Mar 1998)