Languages with fewest irregular verbs

The artificial language Esperanto has no irregular verbs. It was first published by its inventor Dr Ludwig Zamenhof (1859-1917) of Warsaw, Poland in 1887, and is now estimated (by textbook sales) to have 1 million speakers.

 

The even earlier interlanguage, Volapük invented by Johann Martin Schleyer (1831-1912, Germany), also has absolutely regular configuration.

Linguists disagree on the definition of "irregular" - in Spanish, for example, verbs can be considered irregular only in their spelling, although the pronunciation is regular – but it appears that there are no "natural" languages that have no irregular verbs by the widely accepted understanding of the term (i.e., verbs that do not follow the general rules for verb forms (conjugations)).

Turkish has one one irregular verb - imek, "to be" - a fact that helped secure Norris and Ross McWhirter the job as Editor for the Guinness Book of Records. They had met with Sir Hugh Beaver, Chairman of the Guinness Brewery, on 12 September 1954, to discuss their suitability for compiling Sir Hugh's idea of a book of superlatives, and Norris was able to name imek as the only verb in the language with the fewest irregular verbs.