Why are Shtokavian dialects called Shtokavian?

The Shtokavian dialects are named after the specific word used for the interrogative pronoun "what" within that dialect group.12

In these dialects, the form used for "what" is što (or šta), which is pronounced as "shto" in English. This naming convention distinguishes them from the other two primary dialect groups of the region:12
* Chakavian, which uses the form ča ("cha") for "what".12
* Kajkavian, which uses the form kaj for "what".12

While these names are derived from these distinct pronouns, the dialects also differ significantly in their vowels, consonants, word forms, and vocabulary.1