It is same as suffix. Jo shabdansh shbad me anth mein lagkar unke arth mein parivarthan ya visheshta utpan kar dete hein unhe pratya kehte hein. I want to convey that the words that are paced after a word and it makes a change in the meaning, those words are called pratya. Like in eglish in word 'management', 'ment" is the suffix and in Hindi its also same. In 'samajik' 'ik' is pratya.