› [C] a sign that shows what something is like or proves that something exists: a marker of sth The company sees its invitation to join the business forum as a marker of success. › [C, usually singular] something that is used as a comparison to judge or decide things, especially to set a standard for the future: a marker for sth This new-style cookbook was effectively the marker for all the books that followed. › [C] (also marker pen) a thick pen for writing or drawing: a black/permanent/washable marker put/lay/set down a/your marker (for sth) › to show clearly what your opinion or position about something is, and how you plan to act in the future: By entering into this partnership, the company has put down a clear marker for the future. Now is the time for a clear marker to be laid down about levels of executive pay.