The Nandi language, or Kalenjin proper, are a dialect cluster of the Kalenjin branch of the Nilotic language family. In Kenya, where speakers make up 18% of the population, the name Kalenjin, a Nandi expression meaning "I say (to you)", gained prominence in the late 1940s and the early 1950s, when several Kalenjin-speaking peoples united under it. This ethnic consolidation created a major ethnic group in Kenya, and also involved a standardization of the Kenyan Kalenjin dialects. However, since outside Kenya the name Kalenjin has been extended to related languages such as Okiek of Tanzania and Elgon languages of Uganda, it is common in linguistic literature to refer to the languages of the Kenyan Kalenjin peoples as Nandi, after the principal variety. Varieties The Kenyan conception of Kalenjin is an inclusive term for different dialects spoken in the north Rift region of Kenya. Nandi Kipsigis Markweta Naandi (Cemual) (Kenya) Terik Keiyo (Kenya) (North) Tugen (Kenya) Phonology Vowels Kalenjin has a simple five-vowel inventory {a, e, i, o, u}, which is then expanded by the presence of a contrastive [+/-ATR feature], as well as a phonemic vowel length distinction. In (at least) Kipsigis (Toweett 1979) and Nandi (Creider 1989), all five vowels have both [+ATR], and [-ATR] counterparts, but the contrast is neutralized for the vowel [a] in Tugen (Jerono 2012). The neutralization of the [+/-ATR] contrast for this specific vowel is common in other Nilotic languages of the region, such as Maasai of Kenya and Didinga of South Sudan. Kalenjin, like many other African languages, exhibits Advanced Tongue Root harmony. As a result, all vowels in a word have the same [ATR] value. In the rest of the article, Kalenjin words with [-ATR] will be spelled in italics. It is common in the language to use [ATR] distinctions to signal grammatical functions. For example, in Kipsigis, the word for ‘bird’ tàríit with a [-ATR] feature on the vowels forms its plural by changing the value of the [ATR] feature to [+ATR] for all its vowels. Similarly, vowel length is important for certain grammatical distinctions. For example, perfect aspect in the past is signaled through lengthening of the vowel of the subject agreement prefix. Therefore, the only difference between simple and perfect aspect in the past is that the subject agreement prefix is short in the former, but long in the latter. Consonants The following table shows the consonant phonemes of