1. to be unable to just watch (without doing anything); to be unable to look on in silence; to be unable to overlook; to be unable to remain indifferent to
Unable to stand by, the sensible older sister gave a lecture to her younger sister, who seemed lethargic and listless every day, saying, “Why don’t you read a real book with substance for a change, instead of reading cheap celebrity gossip magazines?”— Jreibun