invulnerable comes from Latin invulnerabilis, from in- 'not' plus vulnerabilis 'wounding, that may be wounded', from vulnerare 'to wound', from vulnus 'wound'. Morphologically, the prefixed shape matters: the initial element belongs to the recorded formation and helps explain the modern form's surface analysis. In present English, the adjective sense is "incapable of being wounded, harmed, or overcome", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as vulnerable, and in derivatives such as invulnerably and invulnerability. Its semantic neighborhood includes impervious, unassailable, impregnable, and invincible, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin invulnerabilis and Latin vulnus.