Longman Dictionary of Contemporary English - pen

~1 n 1 an instrument for writing or drawing with ink  (a ballpoint pen | a fountain pen | a felt-tip pen) 2 a small piece of land enclosed by a fence, used for keeping farm animals in  (a sheep pen)  (- see also playpen) 3 put/set pen to paper to begin to write 4 AmE slang penitentiary; a prison ~2 v penned, penning formal to write a letter or note with a pen pen sb/sth up/in phr v 1 to shut an animal in a small enclosed area 2 be penned in to be restricted, as if you are being kept in a small place  (They were penned in watching TV with their parents all night.)