Irregularities and exceptions in Interlingua

These special cases have crept into the language as a result of the effort to keep it naturalistic.

Most of these irregularities also exist in Interlingua's source languages; English, French, Italian, Spanish, Portuguese, and to a lesser extent German and Russian.

Interlingua is notable in the sense that unlike most auxiliary languages, that seek to minimise or eliminate any irregular aspects, Interlingua takes a flexible approach.

Diacritics are permitted when they do not influence the pronunciation of the word borrowed into Interlingua.

Common examples of such words are radios Röntgen (X rays) and kümmel.