S: (v) intervene, step in, interfere, interpose (get involved, so as to alter or hinder an action, or through force or threat of force) "Why did the U.S. not intervene earlier in WW II?"
S: (v) interact (act together or towards others or with others) "He should interact more with his colleagues"
S: (v) act, move (perform an action, or work out or perform (an action)) "think before you act"; "We must move quickly"; "The governor should act on the new energy bill"; "The nanny acted quickly by grabbing the toddler and covering him with a wet towel"