Nay-saying is a term used to describe someone who habitually disagrees or criticizes another person's ideas or plans. Some useful synonyms for nay-say include negativist, pessimist, detractor, fault-finder, carper, and moaner. Negativists are those who always see the negatives and focus solely on the downsides of something. Pessimists are those who anticipate the worst and believe that things will always turn out badly. A detractor is one who actively tries to discourage or disapprove of something. Fault-finders focus solely on the flaws in a new idea. Carpers are those who criticize or complain about something without making an effort to help. Moaners are those who are always grumbling and complaining about something. Whatever the term used, nay-sayers can be a real hindrance to progress and change.