The Spanish junta (“together”) comes from the Latin iunctus for “joined.” If you are together, then you are joined in one form or another.
From the Latin root iunctus, we get the English joint. A joint, after all, is just the exact point where two different things come together!
Both junta and joint have the j‑n-t root, although it’s always fun to remember that both had an i- instead of a j- in Latin. Just like INRI.