Q: What words have their plurals formed by dropping the final letter?


There are a number of words (e.g., "jinni") where there is a variant spelling sans the terminal letter (e.g., "jinn") and where the plural is the same as the singular. I don't think this is in keeping with the spirit of the question.

There are a number of Italian words where the final "o" is dropped to

form a plural
arpeggio capriccio carroccio fascio impresario intarsio latticinio pasticcio preludio scenario seraglio solfeggio

Other words are:

hemiepes n pl hemiepe

:a dactylic tripody having a spondaic third foot or lacking the two

short syllables of the third foot

koruna n pl korun or koruny also korunas

:the basic monetary unit of Czechoslovakia

microstomia also microstomus n pl microstomias also microstomi

:an abnormally small mouth

necropolis n pl necropolises or necropoles also necropoleis or necropoli

:a large elaborate cemetery of an ancient city

samanid n pl samanids or samani

:a member of a 9th and 10th century Persian dynasty ruling from Bokhara

and encouraging literature and art

volksdeutscher n pl volksdeutsche

:a person of German ethnic origin long settled in a central or east

European country, repatriated for political reasons by the Nazi regime, and expelled into West Germany after World II

**** Unless noted otherwise, all words occur in Webster's Third New International Dictionary, Merriam-Webster, Springfield, MA, 1961.

lib/config.php:156: Notice: Undefined variable: accept

lib/DbaDatabase.php:134: Warning: dba_replace() [<a href='function.dba-replace'>function.dba-replace</a>]: You cannot perform a modification to a database without proper access