Irregular Plural Nouns

Irregular plural nouns are the ones, which don’t follow the general rule of merely adding a ‘s’. There are no easy ways to remember them, so they generally have to be memorized.

 

Latin-ate Plurals

Words ending in –is usually follow the original Latin form (basis/bases, crisis/crises) for reasons of euphony.

 SINGULAR  PLURAL
 addendum addenda
alga algae
alumnus alumni
amoeba  amoebae
 antenna antennae
bacterium bacteria
 cactus cacti
 curriculum curricula
 datum data
 fungus fungi
 genus genera
 larva larvae
 memorandum memoranda
radix radices
 referendum  referenda
 stigma  stigmas
 stratum  strata
 thesis  theses
 vortex  vortexes
 vertebra  vertebrae

OTHERS

 SINGULAR  PLURAL
 echo  echoes
embargo  embargoes
 tomato tomatoes
 hero  heroes
 torpedo torpedoes
 potato  potatoes