The law and the good, in European languages, are associated with straight lines; the bad with the crooked. Think about the word crooked itself, literally! Or about right/rectangle, or the Greek ortho- for straight, hence, orthodox as well as orthodontics.
This is why it makes sense that Derecho — Spanish for straight and also for law — comes from the same Latin root that gives us direct.
The “ct” in the original direct turned into a “ch” in Spanish, in the usual pattern of “ct” turning into “ch” as Latin grew into Spanish.
The Spanish Decir (“to say”) comes from the Latin dictio for “word”. Its participle form is dicho — and dicho also means “saying”, in the sense of, a cliche.
Thus decir is another example of the “ct” sound in Latin turning into the “ch” sound in Spanish — and is also related to the English word… dictionary.
The Latin for “eight” is Octo, from which we get the English Octagon.
Since most Latin words with a ‑ct- sound, like Octo, had the ‑ct- turn into a ‑ch- as the language evolved into Spanish, it is no surprise that eight in Spanish is ocho.
This same pattern manifests itself in noche/nocturnal, leche/lactose, and is one of our favorite patterns here at ForNerds!
Suspect and the Spanish equivalent, sospechoso, are easy to identify and obviously the same word, both from the same Latin root, suspectus.
That’s not the interesting part. Rather, as Latin evolved into Spanish, the Latin sound ‑ct- turned into the Spanish ‑ch- sound. Think lactose/leche or octagon/ocho.
And suspect falls exactly into this pattern: the English s‑s-p-ct maps exactly to the Spanish s‑s-p-ch.
An easy way to remember the Spanish decir (to say) is through the word predict.
Predict is, literally, pre — decir — to say beforehand. Pre means “before” and the dict- maps almost exactly to the Spanish decir.
How come the decir has an extra ‑t in it to be predict? Because the Latin predecire took the grammatical form of predicatus and this form grew into English (via the French influence). A prediction in Spanish, after all, is predicho!
Thus, it is a cousin of many English words such as diction and dictionary.