Looking for the proper Latin phrasing of Man's defender

1. How do you say defend in Latin?
2. What does man's defender mean?
3. What is the Latin word for idea?

How do you say defend in Latin?

decens, decentis

appropriate, decent/seemly/becoming, in approved standard.

What does man's defender mean?

Meaning: “defender of mankind.” A true friend, genuine and caring.

What is the Latin word for idea?

Borrowed from English idea, from Latin idea (“a (Platonic) idea; archetype”), from Ancient Greek ἰδέα (idéa, “notion, pattern”), from εἴδω (eídō, “I see”).