A hacek or háček (pronounced "'hatchek") is a diacritic (also known as a "caron") placed over certain letters to indicate palatalization[?] in the orthography of some Slavonic languages, such as Czech, and the Baltic languages and Estonian. It looks like an inverted circumflex and its name means "little hook" in Czech.
... station[?]
South Kentish Town tube station[?]
Swiss Cottage (Metropolitan Line) tube station[?]
Tower of London tube station[?]
Wood Lane (Central Line) tube ...