Plural Form of Words Ending in -us

Plural Form Of Words Ending In -us

Most English words ending in -us, particularly those derived from Latin, replace the -us suffix with -i to form plurals. This is irregular, however: some words that end in -us do not pluralize with -i. Sometimes this is because they are not Latin words, and sometimes due to habit (e.g. campus, plural campuses, anus, plural anuses, are both Latin words that do not pluralize with -i). Conversely, some non-Latin words ending in -us or Latin words that would not have pluralized with -i in Latin are given an -i ending in English. Sometimes this plural becomes widely accepted (e.g. cactus, ubiquitously pluralized as cacti), and in other instances would sound unambiguously incorrect to a native speaker (e.g. *ani versus anuses).

In between these two extremes are words that, despite not supporting a Latin plural on etymological grounds, are nonetheless widely pluralized with -i and as such are not immediately heard as incorrect by a substantial number of native speakers (e.g. octopi as a plural for octopus). The question of whether or not these alternative plural forms can be considered incorrect or not touches on the on-going prescriptivism vs descriptivism debate in linguistics and language education.