lifeguard—
1. a person assigned to watch against accidents to bathers at a beach, etc.:
- When a party bathe, one or two of the best swimmers should be posted as lifeguards.
2. a device attached to a locomotive for sweeping obstructions from the track:
- Had not the lifeguard protected the wheels of the engine the train would have been thrown off the line.
life preserver—
1. a life belt or other device used in saving life at sea:
- Taking a life preserver, I ventured into one of the little canoes.
2. a bludgeon loaded with lead, intended for selfdefense:
- The prisoner was given in charge to the police, a life preserver having been found upon him.
3. smth. that may help a person in a critical situation:
- He was busy preparing a “life preserver” in the form of stolen documents he could use later.
Note: Neither compound fully correlates in meaning with lifesaver—
1. = lifeguard 1:
- …mouth-to-mouth resuscitation, by which a life-saver inflates a victim’s lungs with his own breath.
2. = life preserver 3:
- Again many thanks for the money you sent. It was a life-saver.
3. a candy shaped like a small life-belt:
- The American soldiers gave us chocolate bars, life saver candies, chewing gums…