on ology ▁( the ▁spoken ▁language ) ▁and ▁the ▁number ▁of ▁ph on emes ▁( s ounds ). ▁ ▁Major ▁diction aries ▁ ▁The ▁longest ▁word ▁in ▁any ▁of ▁the ▁major ▁English ▁language ▁diction aries ▁is ▁p neum on oul tr am icro scop ics il ic ov ol cano con ios is , ▁a ▁word ▁that ▁refers ▁to ▁a ▁lung ▁disease ▁contract ed ▁from ▁the ▁in hal ation ▁of ▁very ▁fine ▁sil ica ▁particles , ▁specifically ▁from ▁a ▁vol cano ; ▁med ically , ▁it ▁is ▁the ▁same ▁as ▁sil icos is . ▁The ▁word ▁was ▁deliber ately ▁co ined ▁to ▁be ▁the ▁longest ▁word ▁in ▁English , ▁and ▁has ▁since ▁been ▁used ▁in ▁a ▁close ▁approximation ▁of ▁its ▁originally ▁intended ▁meaning , ▁l ending ▁at ▁least ▁some ▁degree ▁of ▁valid ity ▁to ▁its ▁claim . ▁ ▁The ▁Oxford ▁English ▁Dictionary ▁contains ▁pseud op se ud oh yp op ar ath y roid ism ▁( 3 0 ▁letters ). ▁ ▁Mer ri am - Web ster ' s ▁Colleg iate ▁Dictionary ▁does ▁not ▁contain ▁ant id is est ab lish ment arian ism ▁( 2 8 ▁letters ), ▁as ▁the ▁edit ors ▁found ▁no ▁w ides p read , ▁sust ained ▁usage ▁of ▁the ▁word ▁in ▁its ▁original ▁meaning . ▁The ▁longest ▁word ▁in ▁that ▁dictionary ▁is ▁electro ence phal ograph ically ▁( 2 7 ▁letters ). ▁ ▁The ▁longest ▁non - techn ical ▁word ▁in ▁major ▁diction aries ▁is ▁flo cc in auc ini h il ip il ification ▁at ▁