Word for today
According to Wikipedia, "Perichoresis in Christian theology, refers to the mutual inter-penetration and indwelling of the Father and the Son. The doctrine is based on John's Gospel that 'the Father is in the Son, and the Son in the Father'."
"...in John's apocalypse...the Trinity is central, this time in perichoretic imagery." p. 231, Restoring Integrity in Baptist Churches