Safeguard, n.
Etymology: [Safe = guard: cf. F. sauvegarde.]
1. One who, or that which, defends or protects; defense; protection. Shak. Thy sword, the safeguard of thy brother's throne. Granwille.
2. A convoy or guard to protect a traveler or property.
3. A pass; a passport; a safe-conduct. Shak.
1 other Webster entry under this spelling
Safeguard, v. t.
To guard; to protect. Shak.
Shades of meaning
Fernald has no entry of its own for safeguard; he lists it under defense.
He lists it without comment; the entries above explain its neighbors.