protect (keep safe from harm, injury, or danger): We should do more to protect the environment.
defend (protect a person or place from attack): The government deployed additional troops to defend the borders.
guard (watch over to keep a person or a place safe): The dogs guard the house day and night.
safeguard (keep safe from loss, harm, or damage): I want to find a second job to safeguard against unemployment.
secure (make safe; protect): We should secure the building from intruders.
shield (to protect, especially by forming a shield): The atmosphere shields the earth from bombarding meteorites.