Every academic translator has a common enemy to fight: “false friends.”

False friends are words that appear to be similar in two languages, but their meanings are actually quite different.

They have a common etymological origin, but their definitions changed over time as they moved in different linguistic directions.

I have personally counted more than 50 of them in English and Spanish. They are making headway because of their similarity in sound and, in some cases, spelling, and the proximity of the two languages in some communities in the United States and Latin America. Inexperienced English-to-Spanish translators and vice versa fall in this trap because of their lack of familiarity with both languages.

These words traveled slowly and weren’t a threat when paper dictionaries were the only tools that an academic editor or translator had. Today, they travel at the speed of the Internet.

Here are 10 of the most common “false friends”:

1. Aggressive/agresivo: Be careful with this one if you are talking about violence or behavior. In English, you are describing a pushy person, an abrasive individual or an illness. In Spanish, on the other hand, you are talking about a violent person.

2. Casual/casual: In English, this word means “informal,” “without formalities” or “ceremonies.” In Spanish, it means “unforeseen” (imprevisto) or “by chance” (impredecible). If you hear, for example, “I dressed casually for the party” in English, don’t translate it as “I dressed by chance for the party.”

3. Crime/crimen: If you are a legal translator, law editor or interpreter, the life of a person could be in your hands if you don’t know the nuances of these words.

“Crimen” in Spanish means “murder,” “homicide” or “injury with the intent to kill.” The English “crime,” on the other hand, is defined as “an action harmful to the public good and legally prohibited.” Thus, rape, drug dealing, theft, and battery are crimes and do not necessarily involve murder.

4. Definite/definido: In English, when you want to be positive or express something that is certain, you use “definite”  (“She was definite about her answer”). For something that was “explained” (explicado) or “clearly marked” (claramente marcado) in Spanish, you use “definido.”

5. Disorder/desorden: If you are dealing especially with medical or scientific translation, beware of the differences. One of the words meanings in English is “malady,” “illness” or “disturbance in physical or mental health functions.” In Spanish, it could be “confusion,” “mess,” or “public disturbance.” In non-medical terms, such as “the girl left the room in complete disorder when she went out,” they are synonymous.

6. Elaborate/elaborado: “Complex,” or “worked out in great detail,” are the English meanings of this English word that has a simple rendering in Spanish: “hecho” (made) and “producido industrialmente” (industrially produced). For example: “Me gusta más el pan elaborado en fábrica” (I prefer factory-made bread).

7. Global/global:  The word’s similar spelling makes it irresistible for lazy translators. For starters, the English “global” refers almost exclusively to the whole world. Two of its synonyms are “worldwide” and “universal.” The Spanish means “tomado en conjunto” (taken as a whole). For example, “analizaremos los resultados globales” can be translated as “we will analyze the overall results.” For words like “globalize,” “global village” and “globalize” we use, in that order, “universalizar,” “aldea mundial” and “mundialización”.

8. Ignore/ignorar: Another sneaky friend, “ignorar” has been gaining undeserved popularity among Spanish speakers. In English, it means “disregard” or “do not pay attention.” In Spanish, it means “not to know” (no saber) or “lack of education” (falta de educación). However, the nouns “ignorant” and “ignorance” can be synonymous in both languages.

9. Molest/molestar: By far, one of my favorite “false friends.” My students blush when I give them a sentence to read with “molestar,” which they think has sexual overtones. They think that “mi amigo me molesta mucho en la clase” means “my friend molests me a lot in class.” But they relax when I tell them the real meaning: “My friend bothers me (or annoys me) a lot in class.”

10. Topic/tópico: Despite being so close in spelling, these two words have almost nothing in common. The English “topic” refers to “a subject of conversation or discussion.” The Spanish “tópico” could be a medicine or a chiche.

How can translators avoid falling into the false friends’ trap? The answer sounds obvious, but it’s overlooked by inexperienced translators: realizing that languages, like members of a family, may have a common ancestor, but are different. Another suggestion is that if the word that you are translating sounds similar to one in the target language, beware and dig deeper. It may take you a few more minutes to finish the job, but you might unmask a false friend.