reciprocate
1. [ verb ] alternate the direction of motion of
Examples:

"the engine reciprocates the propeller"

Related terms: move reciprocation
2. [ verb ] act, feel, or give in return
Examples:

"We always invite the neighbors and they never reciprocate!"

Related terms: act return interchange
Similar spelling:   reciprocative
  reciprocal
  reciprocatory
  reciprocation
  reciprocating
  reciprocally
  reciprocality
  reciprocal_ohm
  reciprocity