The researches on the Turkish obsolete words shall provide some contributions to vocabulary and also make some unknown issues regarding the history of language and culture to be evident and help to explain the features of language. Despite the multiplicity and diversity of studies on the other areas of grammar, there is limited research in the area of semantics and especially etymology. This study aims at making a contribution to grammar by classifying the reasons why the verbs that are identified from the Dîvânu Lugâti't-Türk (DLT) and Kutadgu Bilig (KB) indexes and are not in use today have been dead. This study includes in the researchers’ explanations regarding the reasons why the words are no longer in use. The obsolete verbs chosen comparatively from the dictionaries are ordered in eight groups according to the reasons of oblivion. It is noteworthy that there are no obsolete verbs as a result of substituting other verbs since their meanings are rude. A few examples have been given to the forgotten verbs as a result of the fact that nouns from which they are derived are dead. One obsolete verb has been identified as a result of using Turkish equivalence of a foreign word and nine obsolete verbs due to shortness or phonetic reasons. It has been concluded that deaths of verbs (fifty one verbs) stem from, at the very most, social, cultural, religious and historical reasons, etc. Because the action is the same action, no change in the verbs may be foreseen, but in the historical process subtle distinctions have emerged, which has caused some verbs to die over time. It is worth considering that such amounts of verbs have been dead in a language where verbs are well protected, even in the samples regarding Divan poetry and prose in which elements belonging to foreign languages such as Arabic and Persian are intensively present.