Mammoth Uncensored Word List:
18 words ending with ly, 21 letters long

acrocephalosyndactyly antiferromagnetically astrophotographically chemolithotrophically clinicopathologically dendrochronologically electromyographically glottochronologically mechanotheraputically microradiographically nonstereospecifically photolithographically posttranscriptionally psychoimmunologically psychophysiologically psychotherapeutically sphygmomanometrically stereomicroscopically