Honorificabilitudinitatibus

Honorificabilitudinitatibus is the ablative plural of the medieval Latin word honorificabilitudinitas, which can be translated as "the state of being able to achieve honours". It is mentioned by the character Costard in Act V, Scene I of William Shakespeare's Love's Labour's Lost.  As it appears only once in Shakespeare's works, it is a hapax legomenon in the Shakespeare canon. It is also the longest word in the English language featuring alternating consonants and vowels.

The earliest use listed in the Oxford English Dictionary is 1599, by Thomas Nashe: "Physitions deafen our eares with the Honorificabilitudinitatibus of their heauenly Panachaea, their soueraign Guiacum." 

Here is the Shakespeare [Oxford] quotation:

"O, they have lived long on the alms-basket of words.
I marvel thy master hath not eaten thee for a word;
for thou art not long by the head as
honorificabilitudinitatibus: thou art easier
swallowed than a flap-dragon."

- Costard, Love's Labour's Lost, Act V, Scene 1

Reposted from 2010.