2.4 Release time: refers to the time (excluding release rebound time) from the moment of rated voltage applied on the disconnected coil to the moment of closure of the normally closed contacts of the relay, which is generally expressed as "ms".
2.5 Return time: For magnetic retaining relay only, it refers to the time from the moment the rated voltage is applied to the return coil to the moment when the normal closed contact of the relay is closed. See Figure 2.
2.6 Bounce time: generally refers to the time from the instant of contact closure to the stable closure, generally expressed as "ms". See Figure 2.