$ perl longestwords.pl wordsEn.txt
..........
length 21
        antienvironmentalists
        antiinstitutionalists
        counterclassification
        electroencephalograms
        electroencephalograph
        electrotheraputically
        gastroenterologically
        internationalizations
        mechanotheraputically
        microminiaturizations
        microradiographically
length 22
        counterclassifications
        counterrevolutionaries
        electroencephalographs
        electroencephalography
length 23
        disestablismentarianism
        electroencephalographic
length 25
        antidisestablishmentarian
length 28
        antidisestablishmentarianism
19 words total (10 requested).
$