at one
In agreement. They need to be at one when they choose their wedding date.
at one
In agreement, in harmony, as in John and Pat were at one on every subject except her cat, which made him sneeze, or Springtime always makes me feel at one with nature. [1300s]
(be) at ˈone (with somebody/something)
(formal) feel that you completely agree with somebody/something, or that you are part of something: Both political parties are at one on the question of foreign imports.This is the kind of place where you can feel at one with nature. at one
In accord or unity.