The term 'concluding word' refers to a word or phrase that is used to END an argument or discussion. The three crossword solutions for this term are END, ERGO, and THUS. END is a three-letter word that is used to signify the conclusion of something. ERGO is a four-letter Latin word that means 'THEREFORE' or 'HENCE'. Lastly, THUS is also a four-letter word that is used to mean 'in this way' or 'CONSEQUENTLY'. All three words can be used to indicate the END of a discussion or argument.