盾 dùn shield

How it came to be

象形 · Pictogram

A drawing of the thing it means.

The oldest form is a picture of a shield.

Noun for "shield", almost always met in the compound 矛盾 (máodùn) "contradiction/conflict": literally "spear and shield", from the classic idiom about a merchant who claimed his spear could pierce any shield and his shield could block any spear.
后盾 (hòudùn) "backing/support" extends the shield sense metaphorically: 坚强的后盾 "a strong backer".
Also used to write foreign currency names ending in "guilder/gulden", e.g. 印尼盾 (Yìnní dùn) "Indonesian rupiah": an unrelated borrowed use worth noting so you're not confused by it in finance news.