1. (n.) The external hard or firm covering of many invertebrate animals.

2. (n.) The outer integument of a seed; the episperm, or spermoderm.

Philistinism aegis armament armature armor plate bard beaver body armor brassard breastplate buckler bulletproof vest callosity callousness callus chain armor chain mail chitin cloak coat of mail coif corselet cortex cover cuirass elytron episperm flintiness formidable defenses gas mask gauntlet guard habergeon hard heart hard shell hardenedness hardheartedness hardness hardness of heart harness hauberk headpiece heart of stone helm helmet imperviousness induration insensitiveness insensitivity inuredness jamb lorica lorication mail mantle nasal needles obduracy obdurateness panoply pericarp plate plate armor protection protective covering rhinoceros hide rondel safeguard screen scute scutum security shell shelter shield shroud spines stoniness suit of armor test testa thick skin veil visor ward