The term irregularities or exceptions in Interlingua refers to deviations from the logical rules in a few grammatical constructions in the international auxiliary language Interlingua. These oddities are a part of the standard grammar. 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. This feature of the language makes Interlingua more familiar to the speakers of source languages. And at the same time, it makes the language more difficult for others.