+50 Irregular Plural and Singular Nouns List
| Singular | Plural |
| Addendum | Addenda |
| Aircraft | Aircraft |
| Alumna | Alumnae |
| Alumnus | Alumni |
| Analysis | Analyses |
| Antenna | Antennae |
| Antithesis | Antitheses |
| Apex | Apices |
| Appendix | Appendices |
| Axis | Axes |
| Bacillus | Bacilli |
| Bacterium | Bacteria |
| Basis | Bases |
| Bison | Bison |
| Bureau | Bureaux |
| Singular | Plural |
| Cactus | Cacti |
| Child | Children |
| Codex | Codices |
| Concerto | Concerti |
| Corpus | Corpora |
| Crisis | Crises |
| Criterion | Criteria |
| Curriculum | Curricula |
| Datum | Data |
| Deer | Deer |
| Diagnosis | Diagnoses |
| Ellipsis | Ellipses |
| Erratum | Errata |
| Focus | Foci |
| Foot | Feet |
| Singular | Plural |
| Fungus | Fungi |
| Genus | Genera |
| Goose | Geese |
| Graffito | Graffiti |
| Grouse | Grouse |
| Index | Indices |
| Larva | Larvae |
| Libretto | Libretti |
| Locus | Loci |
| Louse | Lice |
| Man | Men |
| Medium | Media |
| Mouse | Mice |
| Nebula | Nebulae |
| Nucleus | Nuclei |
| Singular | Plural |
| Oasis | Oases |
| Ovum | Ova |
| Ox | Oxen |
| Phylum | Phyla |
| Prognosis | Prognoses |
| Quiz | Quizzes |
| Series | Series |
| Sheep | Sheep |
| Species | Species |
| Stimulus | Stimuli |
| Stratum | Strata |
| Swine | Swine |
| Syllabus | Syllabi |
| Synopsis | Synopses |
| Thesis | Theses |
