The Spanish for “chest”, pecho, sounds completely different than the English chest.
The relationship is the Latin -ct- words transforming into -ch- as Latin turned into Spanish. Thus, the pect- maps to pech- exactly. The English word, on the other hand, is taken – unchanged – directly from the Latin.
Also from the same root, in Spanish, es pechuga — the common word for the common food, “chicken breast”!
Leche is a first cousin of the English lactose via a very interesting pattern: the -ct- to -ch- pattern.
Both come from the same Latin root, lactatio (literally, “suckling.”) The -ct- in that root remained unchanged as it entered English (because it entered via the sophisticated French) but that sound almost always turned into a -ch- sound as Latin evolved into Spanish. Thus the l-ct maps to the l-ch almost exactly.
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.
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.
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.
And yes, from the same root we also get, via French, douche, as in, douchebag.
Duct and Ducha both come the same Latin root, ductus, “leading”. More on that one another day.
The transformation happened due to the always-fun pattern of the -ct- words in Latin turning into -ch- words in Spanish. Thus, the d-ct in Latin and English maps almost exactly to the d-ch in Spanish.