Familia Rōmāna, Capitulum Sextum Decimum, Versus XXXVIII - "ventus quī ā tergō flat"

Salvēte amīcī!

In that line, FR defines “ventum secundum“ as “ventus quī ā tergō flat“, as it is in this post’s title. I refered to my dictionary and found that “ventus secundus“ is the wind that blows in the same direction that one wants a ship to go to. Did I miss a second meaning for “tergus“, or is it really saying that it blows “away from one’s back“? I’m not a sailor, but I don’t see why a favorable wind would necessarily blow away from my back…

Grātiās agō vōbīs omnibus!
-John

A “favorable” or “following” wind blows a ship “from behind” (and tergum is neuter).

Oh, it makes sense. Much thanks!