"Straight" in every sense: direction, morality, and law
Encoding Strategies:
linguistic

direct
straight
+
-o
suffix
Derecho means straight and is a cognate of direct0 — both share the core idea of being straight or lined up0.
derecho
straight, upright (not bent or curved)
Going or standing in a straight line, without bending or veering.
- Este árbol ha crecido completamente derecho = This tree has grown completely straight
- Camina derecho = Walk upright / straight
right, right-hand (direction)
The right side of the body — historically the "straight" or "strong" side, as opposed to the left side.
- El futbolista se lastimó el pie derecho = The soccer player injured his right foot
- Tuerza por la primera a la derecha = Turn at the first right
honest, upright, straight (morally straight)
A person who is morally "straight" is honest and upright.
- Mi vecino es un hombre derecho y humilde = My neighbor is an honest, humble man
right, entitlement (an entitlement)
A right or entitlement — what is "straight" or correct that someone may legitimately claim or do.
- Todos los niños tienen derecho a la educación = Every child has the right to an education
- Están en su derecho = They are within their rights
law (the field of law)
The body of rules and principles that define what is straight / correct in society.
- Mi hijo va a estudiar derecho = My son is going to study law