Longman Dictionary of Contemporary English
Wiktionary
n. A pen, often with a thick tip made of felt.
Wikipedia
A marker pen, fineliner, marking pen, felt-tip marker, felt-tip pen, flow, marker or texta (in Australia) or sketch pen (in India), is a pen which has its own ink-source, and a tip made of porous, pressed fibers such as felt. A permanent marker consists of a container (glass, aluminum or plastic) and a core of an absorbent material. This filling serves as a carrier for the ink. The upper part of the marker contains the nib that was made in earlier time of a hard felt material, and a cap to prevent the marker from drying out. Until the early 1990s the most common solvents that were used for the ink were toluene and xylene. These two substances are both harmful and characterized by a very strong smell. Today, the ink is usually made on the basis of alcohols (e.g. 1-propanol, 1-butanol, diacetone alcohol and cresols).
Usage examples of "marker pen".
He returned to the counter and picked up the pile of newsprint and a marker pen.
He found a piece of board in the scattered garbage on the street, drew out a marker pen and started writing.
I transferred the tissue-wrapped toadstool to a Baggie, pausing to search through a kitchen drawer until I found a marker pen.
There was nothing in his packets but a pocket pack of Kleenex and a Magic Marker pen.
She had a pad and a pencil, but she was writing on a plastic sheet with a marker pen.