Nouns ending in 'us' of Greek origin become 'uses'. Hippopotamus becomes 'hippopotamuses'.
Nouns ending in 'us' of Latin origin become 'i'. Cactus becomes 'cacti'.
'Octopus' can be either 'octopuses' or 'octopi', depending upon you consider it to be of Greek or Modern Latin origin.
Nouns ending in 'us' of Latin origin become 'i'. Cactus becomes 'cacti'.
'Octopus' can be either 'octopuses' or 'octopi', depending upon you consider it to be of Greek or Modern Latin origin.


