<u>A superlative adjective</u> is defined as a descriptive term used to express that a noun is at the most extreme level it can reach in a given scenario, whether that is in a positive direction or a negative direction.
There are specific rules for using a superlative adjective and see the attachment below for details.
1) What's <u>the most exciting</u> thing you've done this year?
Since there are three or more syllables, [the + most + adjective] should be added.