Performing, or appropriate to, the office of a protector; as, a guardian care. [1913 Webster]

guardian, n.
1 a defender, protector, or keeper.
2 a person having legal custody of another person and his or her property when that person is incapable of managing his or her own affairs.
3 the superior of a Franciscan convent.

Idiom:
guardian angel a spirit conceived as watching over a person or place.

Derivative:
guardianship n.

Etymology:
ME f. AF gardein, OF garden f. Frank., rel. to WARD, WARDEN

N  safety, security, surety, impregnability, invulnerability, invulnerableness, danger past, danger over, storm blown over, coast clear, escape, means of escape, blow valve, safety valve, release valve, sniffing valve, safeguard, palladium, guardianship, wardship, wardenship, tutelage, custody, safekeeping, preservation, protection, auspices, safe-conduct, escort, convoy, guard, shield, guardian angel, tutelary god, tutelary deity, tutelary saint, genius loci, protector, guardian, warden, warder, preserver, custodian, duenna, chaperon, third person, watchdog, bandog, Cerberus, watchman, patrolman, policeman, cop, dick, fuzz, smokey, peeler, zarp, sentinel, sentry, scout, garrison, guardship, refuge &c, anchor, precaution, quarantine, cordon sanitaire, confidence, protect, take care of, preserve, cover, screen, shelter, shroud, flank, ward, guard, secure, entrench, intrench, fence round, house, nestle, ensconce, take charge of, escort, convoy, garrison, watch, mount guard, patrol, make assurance doubly sure, take up a loose thread, take precautions, double reef topsails, seek safety, take shelter, find shelter, Adj, safe, secure, sure, in safety, in security, on the safe side, under the shield of, under the shade of, under the wing of, under the shadow of one's wing, under cover, under lock and key, out of danger, out of the woods, out of the meshes, out of harm's way, unharmed, unscathed, on sure ground, at anchor, high and dry, above water, unthreatened, unmolested, protected, cavendo tutus, panoplied, snug, seaworthy, weatherproof, waterproof, fireproof, defensible, tenable, proof against, invulnerable, unassailable, unattackable, impenetrable, impregnable, imperdible, inexpugnable, Achillean, safe and sound, scathless, unhazarded, not dangerous, unthreatening, harmless, friendly (cooperative), protecting, protective, guardian, tutelary, preservative, trustworthy, ex abundanti cautela, with impunity, all's well, salva res est, suave mari magno, a couvert, e terra alterius spectare laborem, Dieu vous garde, safety, security, surety, impregnability, invulnerability, invulnerableness, danger past, danger over, storm blown over, coast clear, escape, means of escape, blow valve, safety valve, release valve, sniffing valve, safeguard, palladium, guardianship, wardship, wardenship, tutelage, custody, safekeeping, preservation, protection, auspices, safe-conduct, escort, convoy, guard, shield, guardian angel, tutelary god, tutelary deity, tutelary saint, genius loci, protector, guardian, warden, warder, preserver, custodian, duenna, chaperon, third person, watchdog, bandog, Cerberus, watchman, patrolman, policeman, cop, dick, fuzz, smokey, peeler, zarp, sentinel, sentry, scout, garrison, guardship, refuge &c, anchor, precaution, quarantine, cordon sanitaire, confidence, protect, take care of, preserve, cover, screen, shelter, shroud, flank, ward, guard, secure, entrench, intrench, fence round, house, nestle, ensconce, take charge of, escort, convoy, garrison, watch, mount guard, patrol, make assurance doubly sure, take up a loose thread, take precautions, double reef topsails, seek safety, take shelter, find shelter, Adj, safe, secure, sure, in safety, in security, on the safe side, under the shield of, under the shade of, under the wing of, under the shadow of one's wing, under cover, under lock and key, out of danger, out of the woods, out of the meshes, out of harm's way, unharmed, unscathed, on sure ground, at anchor, high and dry, above water, unthreatened, unmolested, protected, cavendo tutus, panoplied, snug, seaworthy, weatherproof, waterproof, fireproof, defensible, tenable, proof against, invulnerable, unassailable, unattackable, impenetrable, impregnable, imperdible, inexpugnable, Achillean, safe and sound, scathless, unhazarded, not dangerous, unthreatening, harmless, friendly (cooperative), protecting, protective, guardian, tutelary, preservative, trustworthy, ex abundanti cautela, with impunity, all's well, salva res est, suave mari magno, a couvert, e terra alterius spectare laborem, Dieu vous garde.

N  defense, protection, guard, ward, shielding, propugnation, preservation, guardianship, area defense, site defense, self-defense, self-preservation, resistance, safeguard, balistraria, bunker, screen, camouflage, fortification, munition, muniment, trench, foxhole, bulwark, fosse, moat, ditch, entrenchment, intrenchment, kila, dike, dyke, parapet, sunk fence, embankment, mound, mole, bank, sandbag, revetment, earth work, field- work, fence, wall dead wall, contravallation, paling, palisade, haha, stockade, stoccado, laager, sangar, barrier, barricade, boom, portcullis, chevaux de frise, abatis, abattis, abbatis, vallum, circumvallation, battlement, rampart, scarp, escarp, counter-scarp, glacis, casemate, vallation, vanfos, buttress, abutment, shore, breastwork, banquette, curtain, mantlet, bastion, redan, ravelin, vauntmure, advance work, horn work, outwork, barbacan, barbican, redoubt, fort-elage, fort-alice, lines, loophole, machicolation, sally port, hold, stronghold, fastness, asylum, keep, donjon, dungeon, fortress, citadel, capitol, castle, tower of strength, tower of strength, fort, barracoon, pah, sconce, martello tower, peelhouse, blockhouse, rath, wooden walls, bulletproof vest, armored vest, buffer, corner stone, fender, apron, mask, gauntlet, thimble, carapace, armor, shield, buckler, aegis, breastplate, backplate, cowcatcher, face guard, scutum, cuirass, habergeon, mail, coat of mail, brigandine, hauberk, lorication, helmet, helm, bassinet, salade, heaume, morion, murrion, armet, cabaset, vizor, casquetel, siege cap, headpiece, casque, pickelhaube, vambrace, shako, bearskin, panoply, truncheon, garrison, picket, piquet, defender, protector, guardian, bodyguard, champion, knight-errant, Paladin, propugner, bulletproof window, hardened site, defending, defensive, mural, armed, armed at all points, armed cap-a-pie, armed to the teeth, panoplied, iron-plated, ironclad, loopholed, castellated, machicolated, casemated, defended, proof against, armored, ballproof, bulletproof, hardened, defensively, on the defense, on the defensive, in defense, at bay, pro aris et focis, Int, no surrender!, defense not defiance, Dieu defend le droit, fidei defensor, defender of the faith.

N  keeper, custodian, custos, ranger, warder, jailer, gaoler, turnkey, castellan, guard, watchdog, watchman, Charley, chokidar, durwan, hayward, sentry, sentinel, watch and ward, concierge, coast guard, guarda costa, game keeper, escort, bodyguard, protector, governor, duenna, guardian, governess, nurse, nanny, babysitter, catsitter, dogsitter, bonne, ayah.

guardian angel, guardian spirit, legal guardian