[fart_ratty]

Using american-english dictionary from aspell [1] and filtering for lines that only contain lower case letters [2] gives you 77649 words. For four words that gives approx 64 bits of entropy [3].

[1] Probably available on a Linux system at /usr/share/dict/american-english

[2] '^[a-z]+$'

[3] log_2(77649^4)