According to this expert’s page, the diacritical mark that font developers call the “caron” is known as the “háček” to linguists, and (among other names) in the languages in which it is used: Bosnian, Croatian, Czech, Estonian, Latvian, Lithuanian, Serbian, and Slovenian, among others. Wikipedia advances the theory that the name “caron” was made up by combining “caret” and “macron,” and lets that theory stand in the absense of any other compelling explanation. The mark is called “caron” in the context of Unicode.