The longest word in standard English dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis at 45 letters long.

The longest English word that does not contain the letter ‘e’ is floccinaucinihilipilification at 29 letters.

Cabbaged and Fabaceae, each 8 letters long, are the longest words that can be played on a musical instrument.

Aegilops, 8 letters long, is the longest word with its letters arranged in alphabetical order.

Spoonfed, 9 letters long, is the longest word with its letters arranged in reverse alphabetical order.

CIMICIC and CIMICID, each 7 letters long, are the longest words that are exclusively made up of Roman numerals when written in upper case. Among words consisting of only Roman numeral letters, the “highest scoring” are MIMIC (2,102) and IMMIX (2,012).

Overnumerousnesses, 18 letters long, is the longest word that consists of only letters that lack ascenders, descenders and dots in lower case.

Lighttight and hillypilly, each 10 letters long, are the longest words consisting only of letters with ascenders, descenders and dots in lower case.

Tittifill, 9 letters long, is the longest word consisting only of letters with ascenders or dots in lower case.

Honorificabilitudinitatibus, 27 letters long, is the longest word consisting strictly of alternating consonants and vowels.

Dermatoglyphics, misconjugated and uncopyrightable, each 15 letters long, are the longest words in which no letter appears more than once.

Unprosperousness, 16 letters long, is the longest word in which each letter occurs at least twice.

Esophagographers, 16 letter long, is the longest word in which each of its letters occurs twice.

Discrete - discreet is the longest homophonic anagram (2 similarly pronounced words that are spelt differently but sound the same and are composed of the same letters).

Redivider is the longest common palindromic word ( a word reading the same backwards and forwards).

The longest words that are reverse images of each other are stressed and desserts .