While there are more than one million English works, it has been estimated that the average high school graduate knows about 45,000 words, but actively uses between 12,000 and 20,000. With a million words to chose from, there likely is a perfect word to describe what you want to describe, but you may not know it, and more importantly your audience probalby does not know it.
For example, if you are trying to describe something that is shaped like a cup, “cup-shaped” is the obvious, if mundane choice (made in more than 41,807 other patents), but you might also consider calathiform (see, e.g., U.S. Patent Nos. 4,359,965, and 4,457,260) or poculiform (see, e.g., U.S. Patent Nos. 8,008,099 and 8, 500,301). While an unusal word might be fun for patent drafter, is it good or bad for the patent owner? An unusual word can be an opportunity to make an invention sound more important or more complicated (any maybe less obvious?). It could make the priror art appear to be less relevant, and it also provides some alternative words to break out in the claims during prosecution.
The simpler, more widely understood alternative is usually the best choice, but sometimes it may be worth breaking out the dictionary to find the perfect word to add lustre to the invention, and to your prose as well.