Some singular nouns ending in -is form their plural by changing the ending to -es. The table below lists these nouns in both their singular and plural forms to help you learn and remember this spelling pattern easily.
| Singular | Plural |
|---|---|
| acanthosis | acanthoses |
| acidosis | acidoses |
| acropolis | acropolises |
| analysis | analyses |
| anamnesis | anamneses |
| anastomosis | anastomoses |
| anthracosis | anthracoses |
| antithesis | antitheses |
| apotheosis | apotheoses |
| apoptosis | apoptoses |
| arthrosis | arthroses |
| asbestosis | asbestoses |
| axis | axes |
| basis | bases |
| biogenesis | biogeneses |
| biosynthesis | biosyntheses |
| catharsis | catharses |
| cirrhosis | cirrhoses |
| crisis | crises |
| cyanosis | cyanoses |
| cytolysis | cytolyses |
| dialysis | dialyses |
| diathesis | diatheses |
| diuresis | diureses |
| ecchymosis | ecchymoses |
| ellipsis | ellipses |
| embolism (not -is) | — |
| emphasis | emphases |
| endocytosis | endocytoses |
| endometriosis | endometrioses |
| enuresis | enureses |
| epiphysis | epiphyses |
| epistasis | epistases |
| epistaxis | epistaxes |
| exocytosis | exocytoses |
| genesis | geneses |
| glottis | glottises |
| gnosis | gnoses |
| halitosis | halitoses |
| hematopoiesis | hematopoieses |
| hemolysis | hemolyses |
| homeostasis | homeostases |
| hypnosis | hypnoses |
| hypothesis | hypotheses |
| hypostasis | hypostases |
| iris | irises |
| karyokinesis | karyokineses |
| karyolysis | karyolyses |
| kinesis | kineses |
| leukocytosis | leukocytoses |
| lithiasis | lithiases |
| lysis | lyses |
| meiosis | meioses |
| metamorphosis | metamorphoses |
| metaplasis | metaplases |
| metaphysis | metaphyses |
| metastasis | metastases |
| metathesis | metatheses |
| metempsychosis | metempsychoses |
| mitosis | mitoses |
| mimesis | mimeses |
| mycosis | mycoses |
| narcosis | narcoses |
| nares (pl.) | — |
| necrosis | necroses |
| nemesis | nemeses |
| nephrosis | nephroses |
| neurosis | neuroses |
| oasis | oases |
| osmosis | osmoses |
| osteolysis | osteolyses |
| paralysis | paralyses |
| parenthesis | parentheses |
| paresis | pareses |
| pathogenesis | pathogeneses |
| peristalsis | peristalses |
| phagocytosis | phagocytoses |
| phimosis | phimoses |
| photosynthesis | photosyntheses |
| prognosis | prognoses |
| prosthesis | prostheses |
| proteolysis | proteolyses |
| psoriasis | psoriases |
| psychosis | psychoses |
| ptosis | ptoses |
| praxis | praxes |
| sclerosis | scleroses |
| sepsis | sepses |
| stasis | stases |
| symbiosis | symbioses |
| symphysis | symphyses |
| synapsis | synapses |
| synopsis | synopses |
| synthesis | syntheses |
| telekinesis | telekineses |
| testis | testes |
| thesis | theses |
| thoracentesis | thoracenteses |
| thrombosis | thromboses |
| tmesis | tmeses |
| ureterolithiasis | ureterolithiases |
| urolithiasis | urolithiases |
| virosis | viroses |
