noun
: an index consisting of rounded thumb notches cut symmetrically on the fore edge of a book and tabs denoting the letters (as in a dictionary) or sections referred to beginning on the page that faces or forms the base of each notch
noun
: an index consisting of rounded thumb notches cut symmetrically on the fore edge of a book and tabs denoting the letters (as in a dictionary) or sections referred to beginning on the page that faces or forms the base of each notch
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012