互相

each other / mutually / mutual

mutual

each other / one another / mutually / fret on the neck of a pipa 琵琶[pi2 pa5] (a fret on the soundboard is called a 品[pin3])

appearance / portrait / picture / government minister / (physics) phase / (literary) to appraise (esp. by scrutinizing physical features) / to read sb's fortune (by physiognomy, palmistry etc)

interdependent

to pass the buck / to shirk responsibility

mutually shirking responsibilities (idiom); each blaming the other / passing the buck to and fro / each trying to unload responsibilities onto the other

mutual supervision

mutually related / interconnected

interlinked