This resource is great for expanding for vocabulary, and improving your writing skills in Russian. It could also help you win Russian word games. Choose the letter that you want the word to begin with and then how many letters in the Russian word and you can see all the Russian words that fit that criteria.
So if you select letter as A with number of letters as 10, you will get words like: абажурчики, абазинский and 1,100 other words that start with A and have 10 letters. Your results will appear in three columns: the first column is the word, the second column is whether it's singular or plural and third column is the gender.
Separately, we have other resources for finding Russian anagrams, Russian words that end with, Russian words that contain which letters (either together or apart) and loads of learn Russian converters.