In linguistics, an internationalism or international word is a loanword that occurs in several languages (that is, translingually) with the same or at least similar meaning and etymology. These words exist in "several different languages as a result of simultaneous or successive borrowings from the ultimate source". Pronunciation and orthography are similar so that the word is understandable between the different languages.

It is debated how many languages are required for a word to be considered an internationalism. Furthermore, the languages required can also depend on the specific target language at stake. For example, according to Ghil'ad Zuckermann, the most important languages that should include the same lexical item in order for it to qualify as an internationalism in Hebrew are Yiddish, Polish, Russian, French, German and English.

The term is uncommon in English, although English has contributed a considerable number of words to world languages, e.g., the sport terms football, baseball, cricket, and golf.

International scientific vocabulary is a class of terms that contains many internationalisms. For some of them it is known which modern language used them first, whereas for others it is not traceable, but the chronologic sequence is usually of limited practical importance anyway, as almost immediately after their origination they appeared in multiple languages.