Diacritical, dy uh KRIHT uh kuhl, mark is a sign used with letters of the alphabet to show pronunciation or meaning of words. Diacritical marks are a regular part of spelling in many foreign languages. In English, some words borrowed from other languages also use diacritical marks, but the marks are mainly used in dictionaries to show how words are pronounced. Diacritical marks in English include the circumflex, the dieresis, the macron, the tilde, the single dot, and the breve.