Summary: The Latin root *patr* means "father." This Latin root is the word origin of a fair number of English vocabulary words, including [*pater*]nity, [*patter*]n, and [*patr*]on. The root *patr* is easily recalled via the word [*patr*]iotic, as someone who is acting in a [*patr*]iotic fashion is supporting the "father"land.
