Countable Nouns That Start with O and End with SUM

Explore 4 verified English countable nouns starting with O and ending with SUM, including Opossum, Omasum, Odontoglossum and Osteoglossum. 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 OD
1 words
odontoglossum
Starts with OM
1 words
omasum
Starts with OP
1 words
opossum
Starts with OS
1 words
osteoglossum

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