It can be used as a verb as well as a noun.
Meaning: reply quickly ,wittily,angrily(when used as verb), quick angry incisive reply(when used as noun).It means if we describe the way it was said then retort takes the form of verb and if we gave the nature of what was said then it takes the form of noun.
There is also another meaning to Retort.It is also the name of a closed laboratory vessel with an outlet.
Root of the word : tors, tort which means twist.
Synonyms : rejoin, snap, rejoinder,counter,antiphon.
1)The captain retorted by saying that his critics were the kind of people who had never played the sport even at club level tournaments.
2)He retorted to his opposition team's statement.
3)She was shocked at his retort.