Meaning : A familiar name for a person (often a shortened version of a person's given name).
Example :
Joe's mother would not use his nickname and always called him Joseph.
Henry's nickname was Slim.
Synonyms : byname, moniker, nickname, sobriquet, soubriquet
Meaning : The name used to identify the members of a family (as distinguished from each member's given name).
Synonyms : family name, last name, surname
Cognomen ka meaning, vilom shabd, paryayvachi aur samanarthi shabd in Hindi. Cognomen ka matlab kya hota hai?