Countable Nouns That Start with O and End with US

Explore 23 verified English countable nouns starting with O and ending with US, including Octopus, Opus, Omnibus, Onus, Oculus, Osmanthus and Organophosphorus. Sort these count nouns with singular and plural forms by word length for ESL grammar practice, determiner usage, and plural spelling below, or review singular and plural count rules in our noun grammar guide.

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Starts with OB
2 words
obelus
obliquus
Starts with OC4 words
octopus
oculus
ocellus
octonarius
Starts with OM
1 words
omnibus
Starts with ON4 words
onus
oncovirus
oncornavirus
oncus
Starts with OP3 words
opus
opinicus
opulus
Starts with OR4 words
organophosphorus
ornithorhynchus
orthomyxovirus
orthrosanthus
Starts with OS
1 words
osmanthus
Starts with OT
1 words
otocinclus
Starts with OV
2 words
overplus
overfocus
Starts with OZ
1 words
ozothamnus

•Browse Countable Nouns by Letter (A to Z)

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