For an indie dev I think you're approaching this from the wrong direction - you don't want to create a colossal list of objects, it's not practical.
A far more realistic approach would be to conceive your puzzles beforehand, and then think of multiple solutions that a player would logically think of; for example a level where you have to rescue a cat from a tree would logically have players thinking of objects like ladders, nets, pillows, parachutes etc. These are the items you focus on, from here you branch out into synonyms.
Adjectives are incredibly ambitious, the only moderately successful cases I can see are colours and sizes, as webGL can be used to manipulate hue values and C2 can assign custom height/width values.
So in short, don't think of words. Think of levels that will manipulate your player into choosing certain words, and use that as your wordbase before expanding.
It would be wise to include an event that stipulates that if the user enters a word the game does not recognise, the game sends it to a mySQL database that you would periodically access, read, and then patch the game with the new words.
Finally, the "easiest" (as in laziest, but oddly hardest) way would be to simply pick up an Oxford, Collins or Merriam-Webster dictionary and get to work. I cannot fathom how long it would take.