In translation a LOT depends on context. That is the immediate context of the sentence it is used in. But also the broader context of the paragraph or even the episode.

Literally speaking neither “Mano Duro” nor “Man Dura” seem correct or make sense in isolation.

As others have already pointed out the Spanish noun “mano” gendered female corresponds to the English noun “hand” or even a “mitt” (a glove with no individual fingers), but can also be “clout” (as in influence). But in Central American and Western Caribbean usage the Spanish noun “mano” is also gendered male which then translates to the English “mate”, “pal”, “fellow” or even “homeboy”, because it is considered a contraction from “hermano”. So as you might be able to appreciate, it all depends on the context as to which meaning and gender applies.

The Spanish adjective “duro” can be translated in English to: hard, strong, severe, tough, bitter, tight, stiff, arduous, demanding, challenging, awkward, etc.

And depending on the gender applicable to “mano”, the correct usage would be either “mano dura” for a ”severe hand” or “strong clout”, or else “mano duro” for a “tough fellow”.

Unless the second term you asked about “Man Dura” was mangled while copying, as in omitting the ending “o” in “Mano Dura”, it just does not make sense without the context of at least the sentence it is used in.

I grew up and have lived for almost 50 years in Paraguay in the heart of South America. And I also have a license from the Paraguay Supreme Court as translator for Spanish ←→ English and Spanish ←→ German.

When looking up the meaning of foreign words, you should NEVER just take the first option offered in a dictionary! Because further down you might find options that better fit the context, or even give a clue about cultural nuances. In the above examples, my initial assessment was neither was correct. But when I checked the dictionary, I found cultural or geographic reference with a different gender. So I corrected my assessment accordingly.

Another example of the pitfalls of just using the first option offered by the dictionary: When I was a toddler we spent one year in the international student housing at Harvard University. One of our neighbors was a couple from Germany. The wife had only very rudimentary grasp of English and feeling homesick, wanted to bake a “Bienenstich”. One of the main ingredients is sliced almonds. So this poor lady pulled out her pocket dictionary and looked up the English term for ”Mandel”, saw that the English term is “Tonsil”, and went to grocery store wanting to buy “one pound of tonsils”. She came back in tears and asked my mom why she was told to go to the hospital in order to buy tonsils. My mom then explained to her that “tonsils” are those glands at the back of the throat also called “Mandeln” in German, but that the nuts called “Mandeln” in German are actually called “almonds” in English. This was also confirmed when they checked the complete dictionary listing of “Mandel”.

So coming back to your question as to which is correct, “Mano Duro” or “Mano Dura”? My answer is: It all depends on the context! Unless you can provide me with a broader textual and cultural context, I simply can not answer your question with any kind of confidence.

Greetings,
Jessica Nicole