Analyze and comment on the following.Analyze and comment on the three causes of meaning change within the scope of the extra-linguistic factors, each with example word(s) given below. pen, atom, churl, copperhead
（1）HISTORICAL REASON. A WORD IS REMAINED FOR A NAME THOUGH THE MEANING HAS CHANGED BECAUSE THE REFERENT HAS CHANGED. TAKE "PEN" FOR EXAMPLE. ORIGINALLY, IT DENOTED "FEATHER". NOW, THE NAME IS STILL KEPT. ATOM USED TO MEAN, IN GREEK, "ANY OF THE INDIVISIBLE PARTICLE". NOW ATOM IS NOT THE SMALLEST AND CAN BE DIVIDED INTO EVEN SMALLER PARTICLES, HENCE THE ABANDONMENT OF THE ORIGINAL MEANING. 
（2）CLASS REASON. THE ATTITUDES OF CLASSES HAVE ALSO MADE INROADS INTO LEXICAL MEANING IN THE CASE OF ELEVATION OR DEGRADATION. FOR INSTANCE, "CHURL, HUSSY, WENCH, VILLAIN" AS WE ALREADY KNOW WERE ORIGINALLY NEUTRAL IN COLOUR BUT HAVE ALL DOWN-GRADED AS "ILL-MANNERED OR BAD PEOPLE".
（3）PSYCHOLOGICAL REASON. THE ASSOCIATED TRANSFER OF MEANING AND EUPHEMISTIC USE OF WORDS, ETC., ARE OFTEN DUE TO PSYCHOLOGICAL FACTORS. TAKE "COPPERHEAD" FOR EXAMPLE. DURING THE AMERICAN CIVIL WAR IT WAS EMPLOYED TO REFER TO THOSE NORTHERNERS WHO WERE SECRETLY AIDING AND ABETTING THE SOUTH. 
