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 |