Words that resemble one another are common in all of the world’s languages. Through historical trade and relations with neighbouring countries, vocabulary elements have spread far and wide from their original locations. For example, “orange” comes to English from the Far East. The exact origin language is unknown, but it probably started in Telugu, Tamil, or Malayalam. From there it travelled through Persian, Arabic, and Old French to make it to English. So, you see how words can make it halfway around the world to settle in a particular language.
The reason why words in distinct languages resemble one another is that they’re either borrowed loanwords or they share a common ancestry (cognates). What the exact differences are, you can find out below.
Similarities of loanwords and cognates
Both of these terms are used to determine the origin of a particular word. In both cases, the word’s ancestry is traced back to find out where it came from and often, but not always, it came from another language altogether. In adapting new words to a language, there are also often changes made, but whatever phonological adjustments follow, both “loanword” and “cognate” still refer to the particular origin of a word.
Cognates are of special interest to historical linguistics since they can be used to help recreate the ancestors of modern day languages.
Different history, different origin
While both terms refer to the habit of languages to adopt words, their differences start with genetics.
In the broadest terms, loanwords are simply adopted from another language, without any type of a relationship. Take the “orange” example from above – English simply took the word over from French and adapted it. There are a ton of other examples. Keeping with the “genetic” metaphor, loanwords are like step or adopted siblings. So, if English belongs in the Germanic family, but steals words from French or Spanish, then those are considered loanwords.
Cognates, however, are words that share a genetic lineage – they’re more like your true siblings in that both originate from the same source (your mother and father or, in the case of words, a common ancestral language). So, let’s take the example of “father”. In German, it is “Vater” and both of the words originate from a single Proto-Germanic source. The same goes for the Spanish “padre” and French “père”, which both come from the Latin “pater”. In both cases, the words in the different languages are cognate.
Trouble with definitions
As is often the case with linguistic terms, however, there are those who would disagree with such a definition. If you compare David Crystal’s definition of “cognate” to that of Campbell and Mixco’s, you’ll find that they take somewhat different views on the matter. Moving away from linguists, the definitions get even more garbled. To further complicate things, it’s also clear that words that originate from an older version of a language are cognates but are often not viewed as such. For example – “brodor” is Old English for “brother” and, at least according to some definitions, the terms are cognate.
And there are a lot of other problems with providing a concrete definition. If all of the world’s languages are related then looking back far enough, you’ll find a common ancestor for much of modern vocabulary and the definition for “loanword” essentially disappears. Additionally, languages are in constant change. What is today considered French or Spanish, is actually just modern-day Latin. So, where exactly do you draw the line in the constant change to determine where a word originating from an older version becomes a cognate?
Conclusion – Genetics determines the difference
Despite the problems mentioned, the usual view is that cognates and loanwords are distinguished by genetic relationships. Loanwords are simply bits of vocabulary stolen (it’s not like they actually get given back) from an unrelated language to bolster the lexicon. In contrast, cognate words share a common ancestry and are, thus, related in the genetic sense. However, if you’re willing to put in the work, both can actually help you learn your target language, since you’ll find a lot of familiar vocabulary.