Source : Free On-Line Dictionary of Computing

terpri
     
        /ter'pree/ TERminate PRInt line.  [{LISP 1.5} and later,
        {MacLISP}] To output a {newline}.  Still used in {Common
        LISP}.  On some early {operating system}s and hardware, no
        characters would be printed until a complete line was formed,
        so this operation terminated the line and emitted the output.
     
        [{Jargon File}]
     
        (1996-06-24)