ha·pax le·go·me·non 
(hāpăks′ lĭ-gŏmə-nŏn′)
(hāpăks′ lĭ-gŏmə-nŏn′)n. pl. ha·pax le·go·me·na (-nə)
A word or form that occurs only once in the recorded corpus of a given language.
[Greek : hapax, once + legomenon, neuter sing. passive participle of legein, to count, say.]
- externalization
- externalize
- externally
- external phase
- external respiration
- externe
- externship
- exteroceptive
- exteroceptor
- exterritorial
- exterritoriality
- exterritorially
- extinct
- extinction
- extinctive
- extinguish
- Wilhelm I
- Wilhelm II
- Wilhelmina
- Wilhelmshaven
- wilily
- wiliness
- Wilkes
- Wilkes-Barre
- Wilkes Land