Related, is there a high quality plaintext dictionary file for running similar searches? I’ve spent several hours but couldn’t find one that’s both comprehensive and accurate.
FYI, rupturewort is the sole 11-letter word answer to TFA in YAWL; found using:
grep '^[qwertyuiop]*$' word.list |while read -r line; do echo "${#line} ${line}"; done |sort -n | tail
It's 170k English words, no placenames or people's names or anything like that, but does have some that I question how valid they are.
/usr/share/dict/words is always destination zero for words.